@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 {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 {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 {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 {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 {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 {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 {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 {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 {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}
}
