@article {1647,
	title = {Gold Nanoparticle-Assisted Plasmonic Photothermal Therapy Advances towards Clinical Application},
	journal = {The Journal of Physical Chemistry C},
	year = {2019},
	chapter = {15375},
	author = {Ali, M.R. and Wu, Y. and El-Sayed, M.A.}
}
@article {1644,
	title = {Gold nanoparticles in biological optical imaging},
	journal = {Nano Today},
	year = {2019},
	chapter = {120},
	author = {Wu, Y. and Ali, M.R. and Chen, K. and Fang, N. and El-Sayed, M.A.}
}
@article {1650,
	title = {Gold Nanorod-Assisted Photothermal Therapy Decreases Bleeding during Breast Cancer Surgery in Dogs and Cats},
	journal = {Cancers},
	year = {2019},
	author = {Ali, M.R. and Farghali, H.A. and Wu, Y. and El-Sayed, I. and Osman, A.H. and Selim, S.A. and El-Sayed, M.A.}
}
@article {1655,
	title = {Improving the Flow Cytometry-based Detection of the Cellular Uptake of Gold Nanoparticles},
	journal = {Analytical chemistry},
	year = {2019},
	author = {Wu, Y. and Ali, M.R. and Dansby, K. and El-Sayed, M.A.}
}
@article {1649,
	title = {Operando Investigation into Dynamic Evolution of Cathode{\textendash}Electrolyte Interfaces in a Li-Ion Battery},
	journal = {Nano letters},
	year = {2019},
	author = {Chen, D. and Mahmoud, M.A. and Wang, J.H. and Waller, G.H. and Zhao, B. and Qu, C. and El-Sayed, M.A. and Liu, M.}
}
@article {1639,
	title = {Gold Nanorod-Photothermal Therapy Alters Cell Junctions and Actin Network in Inhibiting Cancer Cell Collective Migration},
	journal = {ACS nano},
	year = {2018},
	author = {Y. Wu and Ali, M. R. K. and B. Dong and T. Han and K. Chen and J. Chen and Y. Tang and N. Fang and F. Wang and El-Sayed, M. A.}
}
@article {1345,
	title = {Nanocatalysts Can Change the Number of Electrons Involved in Oxidation-Reduction Reaction with the Nanocages Being the Most Efficient},
	journal = {Journal of Physical Chemistry C},
	volume = {116},
	number = {45},
	year = {2012},
	note = {Times Cited: 0Weng, Guojun Mahmoud, Mahmoud A. El-Sayed, Mostafa A.},
	month = {Nov},
	pages = {24171-24176},
	abstract = {Eosin Y (EY) is a fluorescein derivative dye that can be reduced by accepting either one or two electrons. The one- or two electron reduction potentials have comparable values. The two-electron reduction pathway dominates when sodium borohydride is used, whereas the reduction pathway changes to a one-electron reduction pathway when gold solid (AuNS) or hollow (AuHS) nanosphere catalysts are used. The reduction reaction of EY by borohydride proceeds via one kinetic stage, whereas in the presence of gold nanocatalysts, three different stages are identified. The first stage has the same reaction rate as in the absence of the nanocatalyst, and no one-electron product is observed (absorption peak at 405 nm). The second stage starts when the rate of the disappearance of EY is suddenly increased; a new peak at 405 nm beings to appear. This stage ends when the rate of the disappearance of EY decreases. The third stage has a rate close to that of the first stage, and the EY is reduced again by accepting two electrons. The lifetime of the first stage is greatly affected by the concentration of the nanocatalyst and decreases as the concentration of the nanocatalyst is increased. The conversion ratio of EY to its one electron reduced form is found to increase proportionally with the concentration of the gold nanocatalyst. In the case of using hollow nanospheres as a catalyst, the conversion ratio is found to be 3 times higher than that when using the solid nanospheres due to the cage effect.},
	isbn = {1932-7447},
	doi = {10.1021/jp308869m},
	author = {Weng, G. and Mahmoud, M A and El-Sayed, M. A.}
}
@article {808,
	title = {A Reexamination of Active and Passive Tumor Targeting by Using Rod-Shaped Gold Nanocrystals and Covalently Conjugated Peptide Ligands},
	journal = {ACS Nano},
	volume = {4},
	year = {2010},
	note = {doi: 10.1021/nn102055s},
	month = {2010},
	pages = {5887 - 5896},
	publisher = {American Chemical Society},
	abstract = {The targeted delivery of nanoparticles to solid tumors is one of the most important and challenging problems in cancer nanomedicine, but the detailed delivery mechanisms and design principles are still not well understood. Here we report quantitative tumor uptake studies for a class of elongated gold nanocrystals (called nanorods) that are covalently conjugated to tumor-targeting peptides. A major advantage in using gold as a ?tracer? is that the accumulated gold in tumors and other organs can be quantitatively determined by elemental mass spectrometry (gold is not a natural element found in animals). Thus, colloidal gold nanorods are stabilized with a layer of polyethylene glycols (PEGs) and are conjugated to three different ligands: (i) a single-chain variable fragment (ScFv) peptide that recognizes the epidermal growth factor receptor (EGFR); (ii) an amino terminal fragment (ATF) peptide that recognizes the urokinase plasminogen activator receptor (uPAR); and (iii) a cyclic RGD peptide that recognizes the av?3 integrin receptor. Quantitative pharmacokinetic and biodistribution data show that these targeting ligands only marginally improve the total gold accumulation in xenograft tumor models in comparison with nontargeted controls, but their use could greatly alter the intracellular and extracellular nanoparticle distributions. When the gold nanorods are administered via intravenous injection, we also find that active molecular targeting of the tumor microenvironments (e.g., fibroblasts, macrophages, and vasculatures) does not significantly influence the tumor nanoparticle uptake. These results suggest that for photothermal cancer therapy, the preferred route of gold nanorod administration is intratumoral injection instead of intravenous injection.The targeted delivery of nanoparticles to solid tumors is one of the most important and challenging problems in cancer nanomedicine, but the detailed delivery mechanisms and design principles are still not well understood. Here we report quantitative tumor uptake studies for a class of elongated gold nanocrystals (called nanorods) that are covalently conjugated to tumor-targeting peptides. A major advantage in using gold as a ?tracer? is that the accumulated gold in tumors and other organs can be quantitatively determined by elemental mass spectrometry (gold is not a natural element found in animals). Thus, colloidal gold nanorods are stabilized with a layer of polyethylene glycols (PEGs) and are conjugated to three different ligands: (i) a single-chain variable fragment (ScFv) peptide that recognizes the epidermal growth factor receptor (EGFR); (ii) an amino terminal fragment (ATF) peptide that recognizes the urokinase plasminogen activator receptor (uPAR); and (iii) a cyclic RGD peptide that recognizes the av?3 integrin receptor. Quantitative pharmacokinetic and biodistribution data show that these targeting ligands only marginally improve the total gold accumulation in xenograft tumor models in comparison with nontargeted controls, but their use could greatly alter the intracellular and extracellular nanoparticle distributions. When the gold nanorods are administered via intravenous injection, we also find that active molecular targeting of the tumor microenvironments (e.g., fibroblasts, macrophages, and vasculatures) does not significantly influence the tumor nanoparticle uptake. These results suggest that for photothermal cancer therapy, the preferred route of gold nanorod administration is intratumoral injection instead of intravenous injection.},
	isbn = {1936-0851},
	url = {http://dx.doi.org/10.1021/nn102055s},
	author = {Huang, Xiaohua and Peng, Xianghong and Wang, Yiqing and Wang, Yuxiang and Shin, Dong M and El-Sayed, Mostafa A and Nie, Shuming}
}
@article {1109,
	title = {Rapid Thermal Tuning of Chromophore Structure in Membrane Protein},
	journal = {Journal of Physical Chemistry B},
	volume = {113},
	number = {13},
	year = {2009},
	note = {Wang, Jianping El-Sayed, Mostafa A.},
	month = {Apr},
	pages = {4184-4186},
	abstract = {We show that the configuration and the optical property of the retinal chromophore in bacteriorhodopsin (bR) can be tuned dynamically from the all-trans configuration to the 13-cis by using a nanosecond laser-induced temperature-jump. The rapid bleach in the visible absorption optical density of retinal has an apparent formation time of ca. 170 ns, whereas the relaxation process finishes within tens of ms. The dynamical transition of retinal from the all-trans to 13-cis species is believed to occur as a result of rapid protein conformational change especially in the vicinity of retinal binding site. Our study reveals the intrinsic dynamical aspect of the retinal chromophore with respect to the protein structure.},
	isbn = {1520-6106},
	doi = {10.1021/jp901560m},
	author = {Wang, Jianping and El-Sayed, Mostafa A}
}
@article {1122,
	title = {A new catalytically active colloidal platinum nanocatalyst: The multiarmed nanostar single crystal},
	journal = {Journal of the American Chemical Society},
	volume = {130},
	number = {14},
	year = {2008},
	note = {Mahmoud, Mahmoud A. Tabor, Christopher E. El-Sayed, Mostafa A. Ding, Yong Wang, Zhong Lin},
	month = {Apr},
	pages = {4590-+},
	abstract = {Nanocatalysts that possess large amounts of atoms on sharp corners and edges and high indexed sites are known to be more catalytically active. We report here on a novel yet simple method to synthesize in large yields a very active platinum nanocatalyst; the multiarmed nanostar single crystal. We utilize a seed mediated method using tetrahedral nanoparticles that are also synthesized by a new and simple technique. High-resolution TEM shows that the nanostar has many arms, varying from a few to over 30, whereby even the largest ones :re found to have single-crystal structures. This strongly suggests that they are formed by a growth mechanism of the seed crystals and not by the aggregation of seed crystals, which should produce twinning planes. Due to the reduction reaction of ferricyanide by thiosulfate, the nanostars are found to have an activation energy, which is nearly 60\% of that of the tetrahedral seeds themselves, both having the same PVP capping agent. This is undoubtedly due to the multiarms with edges, corners, and the presence of high indexed facets in the nanostar catalyst.},
	isbn = {0002-7863},
	doi = {10.1021/ja710646t},
	author = {Mahmoud, M A and Tabor, C. E. and El-Sayed, Mostafa A and Ding, Y. and Wang, Z.L.}
}
@article {1144,
	title = {Effect of the lattice crystallinity on the electron-phonon relaxation rates in gold nanoparticles},
	journal = {Journal of Physical Chemistry C},
	volume = {111},
	number = {29},
	year = {2007},
	note = {Huang, Wenyu Qian, Wei El-Sayed, Mostafa A. Ding, Yong Wang, Zhong Lin},
	month = {Jul},
	pages = {10751-10757},
	abstract = {In order to study the importance of surface phonons on the electron-phonon relaxation in plasmonic nanoparticles, the effect of size, shape, and materials have recently been studied. Gold and silver nanoparticles have shown no dependence on size and shape while copper nanoparticles have shown some size dependence. This suggests that the bulk phonons, which are sensitive to the bulk-phase structure, are solely responsible for the relaxation of the hot electron in gold and silver plasmonic nanoparticles. The importance of bulk phonons should depend on the degree of crystallinity. In the present study, we have found that the electron-phonon relaxation rate decreases greatly when polycrystalline prismatic gold nanoparticles are annealed and transformed into nearly single-crystalline nanospheres. The results are explained by the presence of high-density grain boundaries with dense, high-frequency molecular type vibrations which are effective in removing the energy of the excited electrons in the polycrystalline prismatic nanoparticles.},
	isbn = {1932-7447},
	doi = {10.1021/jp0738917},
	author = {Huang, Wenyu and Qian, Wei and El-Sayed, Mostafa A and Ding, Y. and Wang, Z.L.}
}
@article {1181,
	title = {The assignment of the different infrared continuum absorbance changes observed in the 3000-1800-cm(-1) region during the bacteriorhodopsin photocycle},
	journal = {Biophysical Journal},
	volume = {87},
	number = {4},
	year = {2004},
	note = {Garczarek, F Wang, JP El-Sayed, MA Gerwert, K},
	month = {Oct},
	pages = {2676-2682},
	abstract = {The bleach continuum in the 1900-1800-cm(-1) region was reported during the photocycle of bacteriorhodopsin (bR) and was assigned to the dissociation of a polarizable proton chain during the proton release step. More recently, a broad band pass filter was used and additional infrared continua have been reported: a bleach at <2700 cm(-1), a bleach in the 2500-2150-cm(-1) region, and an absorptive behavior in the 2100-1800-cm(-1) region. To fully understand the importance of the hydrogen-bonded chains in the mechanism of the proton transport in bR, a detailed study is carried out here. Comparisons are made between the time-resolved Fourier transform infrared spectroscopy experiments on wild-type bR and its E204Q mutant (which has no early proton release), and between the changes in the continua observed in thermally or photothermally heated water (using visible light-absorbing dye) and those observed during the photocycle. The results strongly suggest that, except for the weak bleach in the 1900-1800-cm(-1) region and >2500 cm(-1), there are other infrared continua observed during the bR photocycle, which are inseparable from the changes in the absorption of the solvent water molecules that are photothermally excited via the nonradiative relaxation of the photoexcited retinal chromophore. A possible structure of the hydrogen-bonded system, giving rise to the observed bleach in the 1900-1800-cm(-1) region and the role of the polarizable proton in the proton transport is discussed.},
	isbn = {0006-3495},
	doi = {10.1529/biophysj.104.046433},
	author = {Garczarek, F. and Wang, Jianping and El-Sayed, Mostafa A and Gerwert, K.}
}
@article {1191,
	title = {Comparison of the dynamics of the primary events of bacteriorhodopsin in its trimeric and monomeric states},
	journal = {Biophysical Journal},
	volume = {83},
	number = {3},
	year = {2002},
	note = {Wang, JP Link, S Heyes, CD El-Sayed, MA},
	month = {Sep},
	pages = {1557-1566},
	abstract = {In this paper, femtosecond pump-probe spectroscopy in the visible region of the spectrum has been used to examine the ultrafast dynamics of the retinal excited state in both the native trimeric state and the monomeric state of bacteriorhodopsin (bR). It is found that the excited state lifetime (probed at 490 nm) increases only slightly upon the monomerization of bR. No significant kinetic difference is observed in the recovery process of the bR ground state probed at 570 nm nor in the fluorescent state observed at 850 nm. However, an increase in the relative amplitude of the slow component of bR excited state decay is observed in the monomer, which is due to the increase in the concentration of the 13-cis retinal isomer in the ground state of the light-adapted bR monomer. Our data indicate that when the protein packing around the retinal is changed upon bR monomerization, there is only a subtle change in the retinal potential surface, which is dependent on the charge distribution and the dipoles within the retinal-binding cavity. In addition, our results show that 40\% of the excited state bR molecules return to the ground state on three different time scales: one-half-picosecond component during the relaxation of the excited state and the formation of the J intermediate, a 3-ps component as the J changes to the K intermediate where retinal photoisomerization occurs, and a subnanosecond component during the photocycle.},
	isbn = {0006-3495},
	author = {Wang, Jianping and Link, Stephan and Heyes, C D and El-Sayed, Mostafa A}
}
@article {853,
	title = {The correlation between emission in freshly prepared porous silicon and the carrier density in silicon water},
	journal = {Asian Journal of Spectroscopy},
	volume = {6},
	year = {2002},
	author = {Zou, Bingsuo and Wang, Jianping and El-Sayed, Mostafa A}
}
@article {851,
	title = {Fourier transform infrared study of the effect of different cations on bacteriorhodopsin protein thermal stability},
	journal = {Biophysical journal},
	volume = {82},
	year = {2002},
	pages = {1598-1606},
	publisher = {Elsevier},
	abstract = {The effect of divalent ion binding to deionized bacteriorhodopsin (dI-bR) on the thermal transitions of the protein secondary structure have been studied by using temperature-dependent Fourier transform infrared (FT-IR) spectroscopy. The native metal ions in bR, Ca2+, and Mg2+, which we studied previously, are compared with Mn2+, Hg2+, and a large, synthesized divalent organic cation, ((Et)3N)2Bu2+. It was found that in all cases of ion regeneration, there is a pre-melting, reversible conformational transition in which the amide frequency shifts from 1665 to 1652cm-1. This always occurs at \~{}80{\textdegree}C, independent of which cation is used for the regeneration. The irreversible thermal transition (melting), monitored by the appearance of the band at 1623cm-1, is found to occur at a lower temperature than that for the native bR but higher than that for acid blue bR in all cases. However, the temperature for this transition is dependent on the identity of the cation. Furthermore, it is shown that the mechanism of melting of the organic cation regenerated bR is different than for the metal cations, suggesting a difference in the type of binding to the protein (either to different sites or different binding to the same site). These results are used to propose specific direct binding mechanisms of the ions to the protein of deionized bR.},
	isbn = {0006-3495},
	doi = {10.1016/S0006-3495(02)75511-2},
	url = {http://dx.doi.org/10.1016/S0006-3495(02)75511-2},
	author = {Heyes, C D and Wang, Jianping and Sanii, L. S. and El-Sayed, Mostafa A}
}
@article {1192,
	title = {Refolding of thermally denatured bacteriorhodopsin in purple membrane},
	journal = {Journal of Physical Chemistry B},
	volume = {106},
	number = {3},
	year = {2002},
	note = {Wang, JP Heyes, CD El-Sayed, MA},
	month = {Jan},
	pages = {723-729},
	abstract = {The change in protein conformational structure and retinal chromophore binding state have been examined by using in situ UV-vis, FTIR, and CD spectroscopies during the thermal denaturation and refolding processes in bacteriorhodopsin (bR) of purple membrane (PM), in its native trimeric and in Triton X-100 solubilized monomeric form. For the trimeric bR, it is found that heating bR through its premelting transition (T > 78 degreesC, T-m{\textquoteright}) does not cause any permanent damage in the protein secondary structure, and a reversible refolding occurs when it cools back to room temperature. For the monomeric bR, it is found that it is less thermally stable than the trimer. There is a significant change in its protein secondary structure and a complete dissociation of retinal occurs irreversibly at a temperature as low as 66 degreesC. In addition, it is found that heating the trimeric bR through its main molten state (T > 96 degreesC, T-m) changes the protein secondary structure so that bR does not refold fully into its original secondary structure. Upon cooling back to room temperature, about 90\% of the bound retinal in native bR recovers after being heated through its premelting transition, whereas only about 12\% of bound retinal recovers if bR is heated above its main melting temperature. It is also found that refolded bR molecules with their retinal chromophore rebound have a photocycle and are capable of pumping protons. Our results also suggest that from its molten state, protein secondary structure refolding precedes retinal rebinding to the Schiff base.},
	isbn = {1520-6106},
	doi = {10.1021/jp013131a},
	author = {Wang, Jianping and Heyes, C D and El-Sayed, Mostafa A}
}
@article {1194,
	title = {Surface-enhanced Raman scattering of molecules adsorbed on gold nanorods: off-surface plasmon resonance condition},
	journal = {Chemical Physics Letters},
	volume = {366},
	number = {1-2},
	year = {2002},
	note = {Nikoobakht, B Wang, JP El-Sayed, MA},
	month = {Nov},
	pages = {17-23},
	abstract = {The Raman spectra of several molecules adsorbed on gold nanospheres (NSs) (12 nm in diameter) and nanorods (NRs) (25 nm x 10 nm) are studied using an off-plasmon resonance excitation condition. The studies are carried out in colloidal solution and on solid substrates. Enhancement factors on the order of 10(4)-10(5) are observed for the adsorbed molecules on the NRs, however, no such enhancement was observed on NSs under similar condition. These factors are two orders of magnitude larger than the calculated value using the Wang and Kerker electromagnetic model. This suggests a contribution from the chemical mechanism in the observed enhancement. (C) 2002 Published by Elsevier Science B.V.},
	isbn = {0009-2614},
	doi = {10.1016/s0009-2614(02)01492-6},
	author = {Nikoobakht, Babak and Wang, Jianping and El-Sayed, Mostafa A}
}
@article {1193,
	title = {Time-resolved long-lived infrared emission from bacteriorhodopsin during its photocycle},
	journal = {Biophysical Journal},
	volume = {83},
	number = {3},
	year = {2002},
	note = {Wang, JP El-Sayed, MA},
	month = {Sep},
	pages = {1589-1594},
	abstract = {The infrared emission observed below 2000 cm(-1) upon exciting retinal in bacteriorhodopsin (bR) is found to have a rise time in the submicrosecond time regime and to relax with two exponential components on the submillisecond to millisecond time scale. These time scales, together with the assignment of this emission to hot vibrations from the all-trans retinal (in bR) and the 13-cis retinal (in the K intermediate), support the recent assignment of the J-intermediate as an electronically excited species (Atkinson et al., J. Phys. Chem. A. 104:4130-4139, 2000) rather than a vibrationally hot K intermediate. A discussion of these time scales of the observed infrared emission is given in terms of the competition between radiative and nonradiative relaxation processes of the vibrational states involved.},
	isbn = {0006-3495},
	author = {Wang, Jianping and El-Sayed, Mostafa A}
}
@article {1197,
	title = {Transition from nanoparticle to molecular behavior: a femtosecond transient absorption study of a size-selected 28 atom gold cluster},
	journal = {Chemical Physics Letters},
	volume = {356},
	number = {3-4},
	year = {2002},
	note = {Link, S El-Sayed, MA Schaaff, TG Whetten, RL},
	month = {Apr},
	pages = {240-246},
	abstract = {The ultrafast electron dynamics of chemically prepared gold nanoclusters with a 28 atom gold core surrounded by 16 glutathione molecules were investigated. After excitation with femtosecond laser pulses these clusters show an induced transient absorption in the visible from 2.58 to 1.65 eV (480-750 nm) with a maximum around 2.07 eV (600 nm). The excited state relaxation shows a biexponential decay with a subpicosecond and a longer nanosecond decay time independent of the laser pump power. These results are different from those observed previously for larger gold nanoparticles, which suggests that the Au-28-glutathione system shows molecular properties. (C) 2002 Elsevier Science B.V. All rights reserved.},
	isbn = {0009-2614},
	doi = {10.1016/s0009-2614(02)00306-8},
	author = {Link, Stephan and El-Sayed, Mostafa A and Schaaff, T. G. and Whetten, R. L.}
}
@article {1199,
	title = {Visible to infrared luminescence from a 28-atom gold cluster},
	journal = {Journal of Physical Chemistry B},
	volume = {106},
	number = {13},
	year = {2002},
	note = {Link, S Beeby, A FitzGerald, S El-Sayed, MA Schaaff, TG Whetten, RL},
	month = {Apr},
	pages = {3410-3415},
	abstract = {The luminescence properties of chemically prepared gold nanoclusters, each composed of a 28-atom core and a glutathione (GSH) adsorbate layer consisting of 16 molecules, were investigated. These clusters show a distinct absorption onset at 1.3 eV corresponding to the opening of an electronic gap within the conduction band (HOMO-LUMO gap). Here we report on the radiative properties of these molecular-like Bald clusters. By using a combination of different detectors with sensitivities in the visible to the infrared (2.0-0.8 eV), a broad luminescence extending over this entire spectral range was observed. Our results further suggest that the luminescence can be separated into two bands with maxima around 1.5 and 1.15 eV indicating that radiative recombination between the ground state and two distinctively different excited states takes place. The: origin of the observed luminescence bands is discussed using a solid state as well as a molecular model for the electronic structure and relaxation of the clusters. The total quantum yield of the luminescence: as measured at ambient temperature was approximated to be about (3.5 +/- 1.0) x 10(-3).},
	isbn = {1520-6106},
	doi = {10.1021/jp014259v},
	author = {Link, Stephan and Beeby, A. and FitzGerald, S. and El-Sayed, Mostafa A and Schaaff, T. G. and Whetten, R. L.}
}
@article {1204,
	title = {Direct observation of charge-transfer dynamics in a conjugated conducting polymer poly (3-octylthiophene)-fullerene composite by time-resolved infrared spectroscopy},
	journal = {Physical Review B},
	volume = {64},
	number = {23},
	year = {2001},
	note = {Wang, JP Li, Y Hong, XY El-Sayed, MA},
	month = {Dec},
	abstract = {Transient infrared-active vibrational (IRAV) modes observed in the pi -conjugated conducting polymers upon photoexcitation are usually used to characterize the dynamics of the photoinduced charge separation and recombination processes. In this paper, the dynamic behavior of photogenerated charge carrier in the poly(3-octylthiophene) (P3OT) conducting polymer doped with fullerene (C(60)) has been studied by using step-scan time-resolved Fourier-transform infrared spectroscopy at room temperature in the 2500-900-cm(-1) (0.31-0.11-eV) frequency region. Upon photoexcitation with a 10-ns laser pulses, it is observed that IRAV modes appear in the similar vibrational frequency regions for pure P3OT and C(60)-doped P3OT; however, the observed IRAV modes is enhanced by 800\% in intensity in the presence of small amount of C(60) (e.g., 10\%). Our results also show that the charge separation occurs instantaneously within the laser pulse width (10 ns), whereas the charge recombination processes occur in the microseconds to a few milliseconds time domain. In addition, the observed enhancement in the IRAV modes upon C(60) doping indicates an enhanced photogeneration efficiency of the charge separation.},
	isbn = {1098-0121},
	doi = {10.1103/PhysRevB.64.235413},
	author = {Wang, Jianping and Li, Y. and Hong, X. Y. and El-Sayed, Mostafa A}
}
@article {1206,
	title = {The effect of metal cation binding on the protein, lipid and retinal isomeric ratio in regenerated bacteriorhodopsin of purple membrane},
	journal = {Photochemistry and Photobiology},
	volume = {73},
	number = {5},
	year = {2001},
	note = {Wang, JP El-Sayed, MA},
	month = {May},
	pages = {564-571},
	abstract = {The effect of metal cation binding on bacteriorhodopsin (bR) in purple membrane has been examined using in situ attenuated total reflection-Fourier transform infrared difference spectroscopy in aqueous media. It is known that adding metal cations to deionized bR regenerates the purple state from its blue state and recovers the proton pump function, During this process, infrared spectral changes in the frequency region of 1800-1000 cm(-1) are monitored. The results reveal that metal cation binding affects the protein conformation, the retinal isomeric composition as well as lipid head groups. It is also observed that metal cation binding induces conformational changes in the alpha (1)-helix region of bR, converting the portion of its alpha (1)-helical domain into beta -turn or disordered coil, In addition, the influence of Ho3+ binding on the protein and lipid is observed to be larger than that of Ca2+, These results suggest that some of the metal cation binding sites are on the membrane lipid domain, while others could be on the intrahelical domain or interhelical loops where the Asp and Glu are located (binding with their COO- groups). Our results also suggest that the removal of the C-terminal of bR increase the accessibility of the binding site of metal cations, which affects protein conformational structure. All these observations are discussed in terms of the two proposals given in the literature regarding the metal cation binding sites.},
	isbn = {0031-8655},
	doi = {10.1562/0031-8655(2001)073<0564:teomcb>2.0.co;2},
	author = {Wang, Jianping and El-Sayed, Mostafa A}
}
@article {1205,
	title = {Temperature-jump investigations of the kinetics of hydrogel nanoparticle volume phase transitions},
	journal = {Journal of the American Chemical Society},
	volume = {123},
	number = {45},
	year = {2001},
	note = {Wang, JP Gan, DJ Lyon, LA El-Sayed, MA},
	month = {Nov},
	pages = {11284-11289},
	abstract = {The dynamics of the deswelling and swelling processes in thermoresponsive poly-N-isopropylacrylamide (pNIPAm) hydrogel nanoparticles have been studied by using time-resolved transmittance measurements, in combination with a nanosecond laser-induced temperature-jump (T-jump) technique. A decrease in the solution transmittance associated with deswelling of the particles has been observed as the solution temperature traverses the volume phase transition temperature of the particles. Upon inducing the T-jump, the deswelling transition only occurs in a small percentage (< 10\%) of the particle volume, which was found to be a thin periphery layer of the particles. The particle deswelling occurs on the microsecond time scale, and as shown previously, the collapse time can be tuned via adding small amounts of hydrophobic component to the particle shell. In contrast, the reswelling of the particles was thermodynamically controlled by bath equilibration, and only small differences in particle reswelling kinetics were found due to sluggish heat dissipation (millisecond time scale) from the sample cell.},
	isbn = {0002-7863},
	doi = {10.1021/ja016610w},
	author = {Wang, Jianping and Gan, D. J. and Lyon, L. A. and El-Sayed, Mostafa A}
}
@article {1207,
	title = {Time-resolved Fourier transform infrared spectroscopy of the polarizable proton continua and the proton pump mechanism of bacteriorhodopsin},
	journal = {Biophysical Journal},
	volume = {80},
	number = {2},
	year = {2001},
	note = {Wang, JP El-Sayed, MA},
	month = {Feb},
	pages = {961-971},
	abstract = {Nanosecond-to-microsecond time-resolved Fourier transform infrared (FTIR) spectroscopy in the 3000-1000-cm(-1) region has been used to examine the polarizable proton continua observed in bacteriorhodopsin (bR) during its photocycle. The difference in the transient FTIR spectra in the time domain between 20 ns and 1 ms shows a broad absorption continuum band in the 2100-1800-cm(-1) region, a bleach continuum band in the 2500-2150-cm(-1) region, and a bleach continuum band above 2700 cm(-1). According to Zundel (G. Zundel, 1994, J. Mol. Struct. 322.33-42), these continua appear in systems capable of forming polarizable hydrogen bonds. The formation of a bleach continuum suggests the presence of a polarizable proton in the ground state that changes during the photocycle. The appearance of a transient absorption continuum suggests a change in the polarizable proton or the appearance of new ones. It is found that each continuum has a rise time of less than 80 ns and a decay time component of similar to 300 mus. In addition, it is found that the absorption continuum in the 2100-1800-cm(-1) region has a slow rise component of 190 ns and a fast decay component of similar to 60 mus. Using these results and those of the recent x-ray structural studies of bR(570) and M-412 (H. Luecke, B. Schobert, H.T. Richter, J.-P. Cartailler, and J. K. Lanyi, 1999, Science 286:255-260), together with the already known spectroscopic properties of the different intermediates in the photocycle, the possible origins of the polarizable protons giving rise to these continua during the bR photocycle are proposed. Models of the proton pump are discussed in terms of the changes in these polarizable protons and the hydrogen-bonded chains and in terms of previously known results such as the simultaneous deprotonation of the protonated Schiff base (PSB) and Tyr185 and the disappearance of water molecules in the proton release channel during the proton pump process.},
	isbn = {0006-3495},
	author = {Wang, Jianping and El-Sayed, Mostafa A}
}
@article {1222,
	title = {The effect of the protein conformation change on bacteriorhodopsin photocycle},
	journal = {Biophysical Journal},
	volume = {78},
	number = {1},
	year = {2000},
	note = {Wang, JP El-Sayed, MAPart 2},
	month = {Jan},
	pages = {159A-159A},
	isbn = {0006-3495},
	author = {Wang, Jianping and El-Sayed, Mostafa A}
}
@article {1226,
	title = {How does a gold nanorod melt?},
	journal = {Journal of Physical Chemistry B},
	volume = {104},
	number = {33},
	year = {2000},
	note = {Link, S Wang, ZL El-Sayed, MA},
	month = {Aug},
	pages = {7867-7870},
	abstract = {Structural transformation of gold nanorods are investigated by high-resolution transmission electron microscopy after they have been exposed to low-energy femtosecond and nanosecond laser pulses in colloidal solution. The pulse energies were below the gold nanorod melting threshold, but allowed early stage shape transformation processes, It is found that while the as-prepared nanorods are defect-free, laser-irradiation induces point and line defects. The defects are dominated by (multiple) twins and stacking faults (planar defects), which are the precursor that drives the nanorods to convert their {110} facets into the more stable {100} and {111} facets and hence minimize their surface energy. These observations suggest that short-laser pulsed photothermal melting begins with the creation of defects inside the nanorods followed by surface reconstruction and diffusion, in contrast with the thermal melting of the rods or the bulk material, where the melting starts at the surface.},
	isbn = {1089-5647},
	doi = {10.1021/jp0011701},
	author = {Link, Stephan and Wang, Z.L. and El-Sayed, Mostafa A}
}
@article {857,
	title = {Origin of emission from porous silicon: Temperature-dependence correlation with proton conductivity},
	journal = {Physical Review B},
	volume = {62},
	year = {2000},
	pages = {16595},
	publisher = {APS},
	abstract = {The excitation, emission, and Fourier transform infrared (FTIR) spectra of freshly prepared and aged porous silicon (PS) are examined. The effects of aging and temperature changing on the emission and excitation spectra of fresh and aged PS samples is also studied. Aging in air is found to result in a redshift in the emission spectrum, but a blueshift in the excitation spectrum. Increasing the temperatures leads to a general decrease in the emission intensities of both samples: however, the green emission of fresh sample shows an unusually large and sudden increase in its intensity at the same temperature at which the proton conductivity in the silicon wafer increases. The temperature dependence of the O-H vibration intensity of silicon wafers shows a sudden decrease at that temperature. These results are consistent with a model in which the excitation leads to the formation of exciton in the confined nanostructure, and the formation of electron and hole that are trapped by surface traps, whose nature is dependent on the chemical composition of the surface (and thus its age). These conclusions are confirmed by the results of the FTIR spectra of the two samples, the temperature dependence of the emission, and its correlation with the proton conductivity in the fresh PS.},
	doi = {10.1103/PhysRevB.62.16595},
	url = {http://link.aps.org/doi/10.1103/PhysRevB.62.16595},
	author = {Zou, Bingsuo and Wang, Jianping and Liu, C. and Zhang, J.Z. and El-Sayed, Mostafa A}
}
@article {1221,
	title = {Proton polarizability of hydrogen-bonded network and its role in proton transfer in bacteriorhodopsin},
	journal = {Journal of Physical Chemistry A},
	volume = {104},
	number = {18},
	year = {2000},
	note = {Wang, JP El-Sayed, MA},
	month = {May},
	pages = {4333-4337},
	abstract = {Room-temperature time-resolved step-scan Fourier Transform Infrared (FTIR) spectroscopy has been used to study the photocycle of native bacteriorhodopsin (bR) suspension in both H2O and D2O. The kinetics of the retinal isomerization, and that of the protonation/deprotonation of the proton acceptor, Asp85, are compared in the mu s to Ins time domain. It is found that hydrogen/deuterium (H/D) isotope exchange does not significantly affect the kinetics of the retinal isomerization and relaxation processes. However, the protonation/deprotonation processes of Asp85 COO- become slower in D2O. We also studied the kinetics of the continuum absorbance change in the 1850-1800 cm(-1) frequency region, which has previously been proposed to correspond to the absorption of the delocalized proton that is involved in the proton transport to the surface during the photocycle. An H/D isotope shift of the frequency range of this continuum absorbance has been confirmed by the observation that the band in the 1850-1800 cm(-1) disappears in the photocycle of bR in D2O. These results could support the previous proposal that the intramolecular proton release pathway consists of an H-bonded network. Our results also suggest that the two independent processes, the transfer of a proton from the Schiff base to Asp85 and the release of a different proton to the extracellular surface, are closely coupled events.},
	isbn = {1089-5639},
	doi = {10.1021/jp994460u},
	author = {Wang, Jianping and El-Sayed, Mostafa A}
}
@article {1223,
	title = {Self-assembly of gold nanorods},
	journal = {Journal of Physical Chemistry B},
	volume = {104},
	number = {36},
	year = {2000},
	note = {Nikoobakht, B Wang, ZL El-Sayed, MA},
	month = {Sep},
	pages = {8635-8640},
	abstract = {Self-assembly of gold nanorods (NRs) with aspect ratio of similar to 4.6 (12 nm in diameter and 50-60 nm in length) has been studied using transmission electron microscopy (TEM). Under appropriate conditions such as nanoparticle concentration, solvent evaporation, narrow size distribution, ionic strength, and surfactant concentration of the parent solution, gold nanorods assemble into one-, two-, and three-dimensional structures. Some of the three-dimensional assemblies extend to superlattices of NRs. The translation and orientation symmetries of the self-assembled structures are determined. The factors affecting the formation of the ordered self-assembly are discussed.},
	isbn = {1089-5647},
	doi = {10.1021/jp001287p},
	author = {Nikoobakht, Babak and Wang, Z.L. and El-Sayed, Mostafa A}
}
@article {1220,
	title = {Surface reconstruction of the unstable {110} surface in gold nanorods},
	journal = {Journal of Physical Chemistry B},
	volume = {104},
	number = {23},
	year = {2000},
	note = {Wang, ZL Gao, RP Nikoobakht, B El-Sayed, MA},
	month = {Jun},
	pages = {5417-5420},
	abstract = {Gold nanorods prepared electrochemically and capped in micelles are examined using high-resolution transmission electron microscopy (TEM), It is found that they have an axial growth direction of [001] and have surfaces made of {100} and the unstable {110} facets. A detailed examination of the defect sites of both of these facets shows that while the defective regions of the stable {100} facets show atom-height steps with no reconstruction, the less stable higher energy {110} surfaces show missing-row reconstruction. The role of micelles in stabilizing the {110} facet in the gold nanorod is briefly discussed.},
	isbn = {1089-5647},
	doi = {10.1021/jp000800w},
	author = {Wang, Z.L. and Gao, R. P. and Nikoobakht, Babak and El-Sayed, Mostafa A}
}
@article {1240,
	title = {Alloy formation of gold-silver nanoparticles and the dependence of the plasmon absorption on their composition},
	journal = {Journal of Physical Chemistry B},
	volume = {103},
	number = {18},
	year = {1999},
	note = {Link, S Wang, ZL El-Sayed, MA},
	month = {May},
	pages = {3529-3533},
	abstract = {Gold-silver alloy nanoparticles with varying mole fractions are prepared in aqueous solution by the co-reduction of chlorauric acid HAuCl4 and silver nitrate AgNO3 with sodium citrate. As the optical absorption spectra of their solutions show only one plasmon absorption it is concluded that mixing of gold and silver leads to a homogeneous formation of alloy nanoparticles. The maximum of the plasmon band blue-shifts linearly with increasing silver content. This fact cannot be explained by a simple linear combination of the dielectric constants of gold and silver within the Mie theory. On the other hand, the extinction coefficient is found to decrease exponentially rather than linearly with increasing gold mole fraction x(Au). Furthermore, the size distribution of the alloy nanoparticles is examined using transmission electron microscopy (TEM). High-resolution TEM (HRTEM) also confirms the formation of homogeneous gold-silver alloy nanocrystals.},
	isbn = {1089-5647},
	doi = {10.1021/jp990387w},
	author = {Link, Stephan and Wang, Z.L. and El-Sayed, Mostafa A}
}
@article {1236,
	title = {Comparison between the polarized Fourier-transform infrared spectra of aged porous silicon and amorphous silicon dioxide films on Si (100) surface},
	journal = {Journal of Molecular Structure},
	volume = {508},
	number = {1-3},
	year = {1999},
	note = {Wang, JP Zou, BS El-Sayed, MA},
	month = {Sep},
	pages = {87-96},
	abstract = {The s- and p-polarized Fourier transform infrared spectra were measured for an aged porous silicon (PS) film on Si (100) surface. The asymmetric stretching and symmetric stretching modes as well as the bending or rocking mode of the Si-O-Si group are studied. The deconvoluted spectra in Si-O-Si asymmetric stretching frequency region at different polarization directions show two pairs of vibrational modes, and can be assigned to the longitudinal-optic (LO) and transverse-optic (TO) pair of the corresponding vibrational modes. The smaller LO-TO pair splitting, the broader bandwidth, and the lower polarization ratio of the PS vibration bands as compared with those observed in an a-SiO2 film on Si wafer, suggest a less ordered SiO2 structure and a shorter range of coulombic interaction in PS. (C) 1999 Elsevier Science B.V. All rights reserved.},
	isbn = {0022-2860},
	doi = {10.1016/s0022-2860(99)00003-4},
	author = {Wang, Jianping and Zou, Bingsuo and El-Sayed, Mostafa A}
}
@article {1235,
	title = {Crystallographic facets and shapes of gold nanorods of different aspect ratios},
	journal = {Surface Science},
	volume = {440},
	number = {1-2},
	year = {1999},
	note = {Wang, ZL Mohamed, MB Link, S El-Sayed, MA},
	month = {Oct},
	pages = {L809-L814},
	abstract = {Crystal structures of gold nanorods synthesized electrochemically using micelles as a capping material have been studied by high-resolution transmission electron microscopy. Short gold nanorods with aspect ratios of 3-7 are enclosed mainly by (100) and (110) facets and their axial growth direction is [001], whereas long gold nanorods of aspect ratios 20-35 are dominated by (111) and (110) facets and their growth axial direction is (112). The short rods are the dominant constituents, whereas the long rods are observed occasionally. Spherical-like Au particles with equivalent mass to the short rods are dominated by (111) and (100) facets with shapes of truncated octahedra, icosahedra and decahedra. The unique (110) facets of Au nanorods are expected to have interesting surface properties. (C) 1999 Elsevier Science B.V. All rights reserved.},
	isbn = {0039-6028},
	doi = {10.1016/s0039-6028(99)00865-1},
	author = {Wang, Z.L. and Mohamed, MB and Link, Stephan and El-Sayed, Mostafa A}
}
@article {1234,
	title = {Effect of different capping environments on the optical properties of CdS nanoparticles in reverse micelles},
	journal = {International Journal of Quantum Chemistry},
	volume = {72},
	number = {4},
	year = {1999},
	note = {Zou, BS Little, RB Wang, JP El-Sayed, MA},
	month = {Apr},
	pages = {439-450},
	abstract = {CdS(E = 2.5 eV) nanoparticles were synthesized in reversed micelles and capped with materials of different band gaps and charge compensation ability: Cd(OH)(2) (4.0 eV), ZnS (3.2 eV), and CdO (2.3 eV). The preparations allowed the examination and comparison of the efficiencies of confinement of the electron and hole by the various capping materials. The absorption and emission spectra of the capped CdS nanoparticles suggest the following: (1) Efficient capping and strong quantum confinement are observed for CdS particles of small size (< 3.8 nm), showing well-resolved photoexcitation spectra; (2) the confinement efficiency improves with capping thickness; (3) although ZnS has smaller band gap than Cd(OH)(2), it was more efficient in surface-charge compensation and it is the best capping agent of the three materials; and (4) the similar band gaps of CdO and CdS resulted spectroscopically in strong mixing between the excited states of these materials. (C) 1999 John Wiley \& Sons, Inc.},
	isbn = {0020-7608},
	doi = {10.1002/(sici)1097-461x(1999)72:4<439::aid-qua27>3.0.co;2-q},
	author = {Zou, Bingsuo and Little, Reginald and Wang, Jianping and El-Sayed, Mostafa A}
}
@article {1247,
	title = {The effect of low and high temperature anneals on the hydrogen content and passivation of Si surface coated with SiO2 and SiN films},
	journal = {Journal of the Electrochemical Society},
	volume = {146},
	number = {5},
	year = {1999},
	note = {Ebong, A Doshi, P Narasimha, S Rohatgi, A Wang, J El-Sayed, MA},
	month = {May},
	pages = {1921-1924},
	abstract = {A detailed comparison of the passivation quality and its dependence on the low and high temperature anneals is presented for various promising Si surface passivation schemes. The passivation schemes investigated in this study include: conventional furnace oxide (CFO), rapid thermal oxide (RTO), belt line oxide (BLO), plasma deposited oxide (PDO), SiN deposited by plasma enhanced chemical vapor deposition (PECVD), CFO/SiN, RTO/SiN, BLO/SiN, PDO/SiN, and RTO/PDO. Passivated low resistivity (1 Ohm cm) p-type silicon samples were subjected to three annealing treatments: (a) 400 degrees C in forming gas (FGA), (b) 730 degrees C in air, and (c) 850 degrees C in air, to simulate heat-treatments, which are typically used for contact anneal, front ohmic contacts, and back surface field formation, respectively, for screen printed silicon solar cells. It is found that the passivation quality of PDO, SiN, RTO, and CFO single layers improves significantly after the 400 degrees C FGA and 730 degrees C thermal cycles with RTO resulting in the lowest surface recombination velocities (S-eff) of 154 and 405 cm/s, respectively. Silicon wafers coated with belt oxide (BLO and BLO/SiN) did not show any improvement in S-eff, which remained at 5000 cm/s due to the inferior quality of BLO formed in compressed air. The oxide/ nitride stack passivation is found to be far superior to single-layer passivation resulting in S-eff Of 70 cm/s for the RTO/SiN scheme after the two high temperature anneals (850 and 730 degrees C). The hydrogen concentration measurements by Fourier transform infrared spectroscopy show a greater decrease in the hydrogen content in the annealed RTO/SiN stack compared to the as-deposited SiN single layer after the 730 and 850 degrees C anneals. A combination of reduced hydrogen content and very low S-eff in the RTO/SiN stack suggests that the release of hydrogen from SiN during the anneal further passivates the RTO/Si interface underneath. (C) 1999 The Electrochemical Society. S0013-4651(98)08-117-8. All rights reserved.},
	isbn = {0013-4651},
	doi = {10.1149/1.1391866},
	author = {Ebong, A. and Doshi, P. and Narasimha, S. and Rohatgi, A. and Wang, Jianping and El-Sayed, Mostafa A}
}
@article {1244,
	title = {Electron dynamics in gold and gold-silver alloy nanoparticles: The influence of a nonequilibrium electron distribution and the size dependence of the electron-phonon relaxation},
	journal = {Journal of Chemical Physics},
	volume = {111},
	number = {3},
	year = {1999},
	note = {Link, S Burda, C Wang, ZL El-Sayed, MA},
	month = {Jul},
	pages = {1255-1264},
	abstract = {Electron dynamics in gold nanoparticles with an average diameter between 9 and 48 nm have been studied by femtosecond transient absorption spectroscopy. Following the plasmon bleach recovery after low power excitation indicates that a non-Fermi electron distribution thermalizes by electron-electron relaxation on a time scale of 500 fs to a Fermi distribution. This effect is only observed at low excitation power and when the electron distribution is perturbed by mixing with the intraband transitions within the conduction band (i.e., when the excitation wavelength is 630 or 800 nm). However, exciting the interband transitions at 400 nm does not allow following the early electron thermalization process. Electron thermalization with the lattice of the nanoparticle by electron-phonon interactions occurs within 1.7 ps under these conditions, independent of the excitation wavelength. In agreement with the experiments, simulations of the optical response arising from thermalized and nonthermalized electron distributions show that a non-Fermi electron distribution leads to a less intense bleach of the plasmon absorption. Furthermore, the difference between the response from the two electron distributions is greater for small temperature changes of the electron gas (low excitation powers). No size dependence of the electron thermalization dynamics is observed for gold nanoparticles with diameters between 9 and 48 nm. High-resolution transmission electron microscopy (HRTEM) reveals that these gold nanoparticles possess defect structures. The effect of this on the electron-phonon relaxation processes is discussed. 18 nm gold-silver alloy nanoparticles with a gold mole fraction of 0.8 are compared to 15 nm gold nanoparticles. While mixing silver leads to a blue-shift of the plasmon absorption in the ground-state absorption spectrum, no difference is observed in the femtosecond dynamics of the system. (C) 1999 American Institute of Physics. [S0021-9606(99)71427-3].},
	isbn = {0021-9606},
	doi = {10.1063/1.479310},
	author = {Link, Stephan and Burda, Clemens and Wang, Z.L. and El-Sayed, Mostafa A}
}
@article {1238,
	title = {Temperature jump-induced secondary structural change of the membrane protein bacteriorhodopsin in the premelting temperature region: A nanosecond time-resolved Fourier transform infrared study},
	journal = {Biophysical Journal},
	volume = {76},
	number = {5},
	year = {1999},
	note = {Wang, JP El-Sayed, MA},
	month = {May},
	pages = {2777-2783},
	abstract = {The secondary structural changes of the membrane protein, bacteriorhodopsin, are studied during the premelting reversible transition by using laser-induced temperature jump technique and nanosecond time-resolved Fourier transform infrared spectroscopy. The helical structural changes are triggered by using a 15 degrees C temperature jump induced from a preheated bacteriorhodopsin in D2O solution at a temperature of 72 degrees C. The structural transition from alpha(II)- to alpha(I)-helices is observed by following the change in the frequency of the amide I band from 1667 to 1651 cm(-1) and the shift in the frequency of the amide II vibration from 1542 cm(-1) to 1436 cm(-1) upon H/D exchange. It is found that although the amide I band changes its frequency on a time scale of <100 ns, the H/D exchange shifts the frequency of the amide II band and causes a complex changes in the 1651-1600 cm(-1) and 1530-1430 cm(-1) frequency region on a longer time scale (>300 ns). Our result suggests that in this "premelting transition" temperature region of bacterioriorhodopsin, an intrahelical conformation conversion of the alpha(II) to alpha(I) leads to the exposure of the hydrophobic region of the protein to the aqueous medium.},
	isbn = {0006-3495},
	author = {Wang, Jianping and El-Sayed, Mostafa A}
}
@article {1239,
	title = {Temperature-dependent size-controlled nucleation and growth of gold nanoclusters},
	journal = {Journal of Physical Chemistry A},
	volume = {103},
	number = {49},
	year = {1999},
	note = {Mohamed, MB Wang, ZL El-Sayed, MA},
	month = {Dec},
	pages = {10255-10259},
	abstract = {The electrochemical method of synthesis of gold nanorods in micelles gives substrate solutions that upon spotting and heating on a transmission electron microscope (TEM) substrate result in the nucleation and growth of small gold nanoclusters of narrow size distribution. The size of the nanoclusters, and not their numbers, is found to increased with increasing final temperature to which the substrate is heated. The data are fitted to a mechanism, based on Ostwald ripening in which atomic gold diffusion followed by nucleation on nucleating sites leads to the formation of these small clusters.},
	isbn = {1089-5639},
	doi = {10.1021/jp9919720},
	author = {Mohamed, MB and Wang, Z.L. and El-Sayed, Mostafa A}
}
@article {1237,
	title = {Time-resolved Fourier-transform infrared and visible luminescence spectroscopy of photoexcited porous silicon},
	journal = {Physical Review B},
	volume = {59},
	number = {7},
	year = {1999},
	note = {Wang, JP Song, L Zou, BS El-Sayed, MA},
	month = {Feb},
	pages = {5026-5031},
	abstract = {In order to identify the luminescent centers in aged porous silicon, both the time-resolved vibration spectra in the 750-2000-cm(-1) region and the visible luminescence spectra are studied for the same sample in the 0-440-mu s time domain. Laser excitation gives rise to emission characteristics of the porous silicon as well as strong bleach in the infrared spectrum in the region of the ground-stale silicon-oxygen stretching vibration frequencies at 1100 and 1235 cm(-1). In addition, new transient absorption bands appear in this region as a result of the laser excitation. Three characteristic Lifetimes in the decay of the bleach band at 1235 cm(-1) are observed on the 1-, 10-, and 100-mu s time scale. These are similar to the observed decay times of the photoluminescence from porous silicon. These results suggest that the emitting centers in aged porous silicon are trapped excitation sites in an inhomogeneously defected oxidized silicon surface. [S0163-1829(99)09207-3].},
	isbn = {0163-1829},
	doi = {10.1103/PhysRevB.59.5026},
	author = {Wang, Jianping and Song, Li and Zou, Bingsuo and El-Sayed, Mostafa A}
}
@article {1252,
	title = {Kinetically controlled growth and shape formation mechanism of platinum nanoparticles},
	journal = {Abstracts of Papers of the American Chemical Society},
	volume = {215},
	year = {1998},
	note = {Petroski, JM Wang, ZL Green, TC El-Sayed, MAPart 2},
	month = {Apr},
	pages = {U176-U176},
	isbn = {0065-7727},
	author = {Petroski, J. M. and Wang, Z.L. and Green, T.C. and El-Sayed, Mostafa A}
}
@article {1249,
	title = {Shape transformation and surface melting of cubic and tetrahedral platinum nanocrystals},
	journal = {Journal of Physical Chemistry B},
	volume = {102},
	number = {32},
	year = {1998},
	note = {Wang, ZL Petroski, JM Green, TC El-Sayed, MA},
	month = {Aug},
	pages = {6145-6151},
	abstract = {We report transmission electron microscopic studies of in-situ temperature-induced shape transformation and melting behavior of polymer-capped cubic and tetrahedral nanocrystals. Our results indicate that the surface-capping polymer is removed by annealing the specimen at temperatures between 180 and 250 degrees C. The particle shapes show no change up to similar to 350 degrees C. In the temperature range between 350 and 450 degrees C, a small truncation occurs in the particle shapes but no major shape transformation is observed. The particle shapes experience a dramatic transformation into spherical-like shapes when the temperature is raised above similar to 500 degrees C, where surface diffusion or surface premelting (softening) takes place. Above 600 degrees C, surface melting becomes obvious leading to coalescence of the surfaces of neighboring nanocrystals and a decrease in the volume occupied by the assembled nanocrystals. The surface melting forms a liquid layer a few atomic layers deep around the still solid core of the nanocrystal. This temperature is much lower than the melting point of bulk metallic platinum (1769 degrees C). The reduction in the melting temperature is discussed in terms of the surface tension of the solid-liquid interface (gamma(SL)). For an 8 nm diameter Pt nanocrystal, gamma(SL) is calculated to be 2.0 N m(-1) at 650 degrees C, which is smaller than that of the bulk solid-vapor metal surface tension (gamma(sv)). This reduction is proposed to be due to the compensation of the increase in gamma(sv) of the nanocrystal by the wetting effect at the solid-liquid interface.},
	isbn = {1089-5647},
	doi = {10.1021/jp981594j},
	author = {Wang, Z.L. and Petroski, J. M. and Green, T.C. and El-Sayed, Mostafa A}
}
@article {1259,
	title = {A Comparison of the Photoelectric Current Responses Resulting from the Proton Pumping Process of Bacteriorhodopsin under Pulsed and CW Laser Excitations},
	journal = {The Journal of Physical Chemistry B},
	volume = {101},
	year = {1997},
	note = {doi: 10.1021/jp972475r},
	month = {1997},
	pages = {10599 - 10604},
	publisher = {American Chemical Society},
	abstract = {When excited with a pulsed laser, an electric field-oriented bacteriorhodopsin (bR) film on an indium-tin oxide (ITO) conductive electrode generates a photocurrent composed of at least three different components:  B1 (<100 ps), B2 (60 μs), and B3 (ms). When excited with an electronic shutter modulated CW light pulse (>200 ms in duration), a differential photocurrent (components D1 and D2 with decay times in milliseconds) is observed from the bR film. D1 is observed when the CW light is turned on, and D2 is observed when the CW light is turned off. In this paper, we compare the amplitudes and lifetimes of B2, B3, and D1 at various values of pH and ionic strength of the electrolyte solution in which the photocurrent is measured. It is found that changing the film orientation changes the polarity (sign) of B1 and B2, while it does not affect the polarity of B3 and D1. It is also found that B3 and D1 change their polarity upon changing the pH of electrolyte solution, whereas B1 and B2 do not. These results suggest that the origin of B3 and D1 is different from that of B1 and B2. Our results suggest that B3 and D1 are due to the formation of a transient proton capacitor between the two ITO electrodes resulting from the proton pumping in bR. The magnitude and sign of B3 and D1 are determined by the transient proton concentration change (accumulation or disappearance) occurring near the bR-modified ITO electrode interface on the millisecond time scale. The change of sign in B3 and D1 as a function of pH is due to the sequence of proton release/uptake in the bR photocycle:  It first releases protons into the aqueous solution at high pH, while it first takes up protons from the aqueous solution at low pH. The effects of buffer and ionic strength on B3 and D1 are discussed in terms of the kinetics of proton release/uptake and of the transportation of positive and negative ions in the electrolyte solution.},
	isbn = {1520-6106},
	url = {http://dx.doi.org/10.1021/jp972475r},
	author = {Wang, Jianping and Song, Li and Yoo, Seoung-Kyo and El-Sayed, Mostafa A}
}
@article {868,
	title = {Electron Dynamics of Passivated Gold Nanocrystals Probed by Subpicosecond Transient Absorption Spectroscopy},
	journal = {The Journal of Physical Chemistry B},
	volume = {101},
	year = {1997},
	note = {doi: 10.1021/jp962923f},
	month = {1997},
	pages = {3713 - 3719},
	publisher = {American Chemical Society},
	abstract = {The electronic dynamics of gold nanocrystals, passivated by a monolayer of alkylthiol(ate) groups, were studied by transient spectroscopy after excitation with subpicosecond laser pulses. Three solution-phase gold samples with average particle size of 1.9, 2.6, and 3.2 nm with size distribution less than 10\% were used. The photoexcitation in the intraband (surface plasmon region) leads to the heating of the conduction electron gas and its subsequent thermalization through electron?electron and electron?phonon interaction. The results are analyzed in terms of the contribution of the equilibrated ?hot? electrons to the surface plasmon resonance of gold. A different spectral response was observed for different sizes of gold nanoparticles. The results were compared to the dynamics of the large (30 nm diameter) gold nanocrystals colloidal solution. The size-dependent spectral changes are attributed to the reduction of the density of states for small nanoparticles. The observed variation in the kinetics of the cooling process in gold nanoparticles with changing the laser intensity is attributed to the temperature dependence of the heat capacity of the electron gas.The electronic dynamics of gold nanocrystals, passivated by a monolayer of alkylthiol(ate) groups, were studied by transient spectroscopy after excitation with subpicosecond laser pulses. Three solution-phase gold samples with average particle size of 1.9, 2.6, and 3.2 nm with size distribution less than 10\% were used. The photoexcitation in the intraband (surface plasmon region) leads to the heating of the conduction electron gas and its subsequent thermalization through electron?electron and electron?phonon interaction. The results are analyzed in terms of the contribution of the equilibrated ?hot? electrons to the surface plasmon resonance of gold. A different spectral response was observed for different sizes of gold nanoparticles. The results were compared to the dynamics of the large (30 nm diameter) gold nanocrystals colloidal solution. The size-dependent spectral changes are attributed to the reduction of the density of states for small nanoparticles. The observed variation in the kinetics of the cooling process in gold nanoparticles with changing the laser intensity is attributed to the temperature dependence of the heat capacity of the electron gas.},
	isbn = {1520-6106},
	url = {http://dx.doi.org/10.1021/jp962923f},
	author = {Logunov, Stephan L. and Ahmadi, Temer S. and El-Sayed, Mostafa A and Khoury, J. T. and Whetten, R. L.}
}
@article {874,
	title = {Molecular Mechanism of the Differential Photoelectric Response of Bacteriorhodopsin},
	journal = {The Journal of Physical Chemistry B },
	volume = {101},
	year = {1997},
	note = {doi: 10.1021/jp962111j},
	month = {1997},
	pages = {3420 - 3423},
	publisher = {American Chemical Society},
	abstract = {In order to determine the molecular origin of the differential photocurrent from bacteriorhodopsin (bR), the photoelectric response of bR film deposited on an indium tin oxide (ITO) conductive glass electrode under CW excitation is compared with that under pulsed laser excitation at different pH and with opposite membrane orientation with respect to the ITO electrode surface. The characteristics (sign and magnitude) of the dominant component of the differential photocurrent (appearing on the millisecond time scale) are found to correlate with the process of proton release into, or uptake from, the aqueous solution during the photocycle under different experimental conditions. This suggests that the differential current results mainly from the change in the H+ concentration at the bR?ITO electrode interface.In order to determine the molecular origin of the differential photocurrent from bacteriorhodopsin (bR), the photoelectric response of bR film deposited on an indium tin oxide (ITO) conductive glass electrode under CW excitation is compared with that under pulsed laser excitation at different pH and with opposite membrane orientation with respect to the ITO electrode surface. The characteristics (sign and magnitude) of the dominant component of the differential photocurrent (appearing on the millisecond time scale) are found to correlate with the process of proton release into, or uptake from, the aqueous solution during the photocycle under different experimental conditions. This suggests that the differential current results mainly from the change in the H+ concentration at the bR?ITO electrode interface.},
	isbn = {1520-6106},
	url = {http://dx.doi.org/10.1021/jp962111j},
	author = {Wang, Jianping and Yoo, Seoung-Kyo and Song, Li and El-Sayed, Mostafa A}
}
@article {871,
	title = {Steps, ledges and kinks on the surfaces of platinum nanoparticles of different shapes},
	journal = {Surface science},
	volume = {380},
	year = {1997},
	pages = {302-310},
	publisher = {Elsevier},
	abstract = {Platinum nanoparticles with a high percentage of cubic-, tetrahedral- and octahedral-like shapes, respectively, have been synthesized by a shape-controlling technique that we developed recently [Ahmadi et al., Science 272 (June 1996) 1924]. High resolution transmission electron microscopy (HRTEM) is used here to directly image the atomic scale structures of the surfaces of these particles with different shapes. The truncated shapes of these particles are mainly defined by the {100}, {111}, and {110} facets, on which numerous atom-high surface steps, ledges and kinds have been observed. This atomic-scale fine structure of the surfaces of these particles is expected to play a critical role in their catalytic activity and selectivity.},
	isbn = {0039-6028},
	doi = {10.1016/S0039-6028(97)05180-7 },
	author = {Wang, Z.L. and Ahmad, TS and El-Sayed, Mostafa A}
}
@article {877,
	title = {{\textquotedblleft}Cubic{\textquotedblright} Colloidal Platinum Nanoparticles},
	journal = {Chemistry of Materials},
	volume = {8},
	year = {1996},
	note = {doi: 10.1021/cm9601190},
	month = {1996},
	pages = {1161 - 1163},
	publisher = {American Chemical Society},
	abstract = {Cubic platinum nanoparticles (4-18 nm) have been synthesized for the first time in solution by the controlled reduction of K2PtCl4 with hydrogen gas in the presence of sodium polyacrylate as a capping material. The nanoparticles are found to have fee structures, similar to the bulk metal with {100} facets.},
	isbn = {0897-4756},
	doi = {10.1021/cm9601190},
	url = {http://dx.doi.org/10.1021/cm9601190},
	author = {Ahmadi, Temer S. and Wang, Z.L. and Henglein, A. and El-Sayed, Mostafa A}
}
@article {862,
	title = {Shape-Controlled Synthesis of Colloidal Platinum Nanoparticles},
	journal = {Science (New York, N.Y.)},
	volume = {272},
	year = {1996},
	month = {1996 Jun 28},
	pages = {1924-6},
	abstract = {The shapes and sizes of platinum nanoparticles were controlled by changes in the ratio of the concentration of the capping polymer material to the concentration of the platinum cations used in the reductive synthesis of colloidal particles in solution at room temperature. Tetrahedral, cubic, irregular-prismatic, icosahedral, and cubo-octahedral particle shapes were observed, whose distribution was dependent on the concentration ratio of the capping polymer material to the platinum cation. Controlling the shape of platinum nanoparticles is potentially important in the field of catalysis.},
	issn = {1095-9203},
	doi = {10.1126/science.272.5270.1924},
	author = {Ahmadi, Temer S. and Wang, Z.L. and Green, T.C. and Henglein, A. and El-Sayed, Mostafa A}
}
@article {1276,
	title = {Binding of, and Energy-Transfer Studies from Retinal to, Organic Cations in Regenerated Reduced Bacteriorhodopsin},
	journal = {The Journal of Physical Chemistry},
	volume = {98},
	year = {1994},
	note = {doi: 10.1021/j100088a040},
	month = {1994},
	pages = {9339 - 9344},
	publisher = {American Chemical Society},
	abstract = {See http://dx.doi.org/10.1021/j100088a040 for article{\textquoteright}s front page in lieu of an abstract},
	isbn = {0022-3654},
	doi = {doi: 10.1021/j100088a040},
	url = {http://dx.doi.org/10.1021/j100088a040},
	author = {Wu, Shuguang and El-Sayed, Mostafa A}
}
@article {1280,
	title = {Recording of transient gratings using the short lived bacteriorhodopsin photocycle intermediates},
	journal = {Advanced Materials},
	volume = {5},
	year = {1993},
	month = {1993},
	pages = {838 - 842},
	publisher = {WILEY-VCH Verlag GmbH},
	abstract = {Bacteriorhodopsin, a light-transducing protein in the purple membrane of Halobacterium halobium, has unique properties that make it a potentially attractive material for use in optical imaging and processing. A transient diffraction grating based on the K intermediate of the bacteriorhodopsin photocycle has been produced on the nanosecond time scale. The diffraction efficiency, which would be sufficient for pattern recognition for example, was measured and the intensity dependence assessed.},
	isbn = {1521-4095},
	doi = {10.1002/adma.19930051111},
	url = {http://dx.doi.org/10.1002/adma.19930051111},
	author = {Wu, Shuguang and Br{\"a}uchle, Christoph and El-Sayed, Mostafa A}
}
