@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 {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 {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 {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 {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 {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 {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 {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}
}
