@article {1211,
	title = {The relaxation dynamics of the excited electronic states of retinal in bacteriorhodopsin by two-pump-probe femtosecond studies},
	journal = {Proceedings of the National Academy of Sciences of the United States of America},
	volume = {98},
	number = {15},
	year = {2001},
	note = {Logunov, SL Volkov, VV Braun, M El-Sayed, MA},
	month = {Jul},
	pages = {8475-8479},
	abstract = {We present the results of two-pump and probe femtosecond experiments designed to follow the relaxation dynamics of the lowest excited state (S-1) populated by different modes. In the first mode, a direct (S-0 --> S-1) radiative excitation of the ground state is used. In the second mode, an indirect excitation is used where the S-1 state is populated by the use of two femtosecond laser pulses with different colors and delay times between them. The first pulse excites the S-0 --> S-1 transition whereas the second pulse excites the S-1 --> S-n transition. The nonradiative relaxation from the S-n state populates the lowest excited state. Our results suggest that the S1 state relaxes faster when populated nonradiatively from the S-n state than when pumped directly by the S-0 --> S-1 excitation. Additionally, the S-n --> S-1 nonradiative relaxation time is found to change by varying the delay time between the two pump pulses. The observed dependence of the lowest excited state population as well as its dependence on the delay between the two pump pulses are found to fit a kinetic model in which the S-n state populates a different surface (called Si) than the one being directly excited (S-1). The possible involvement of the A(g) type states, the J intermediate, and the conical intersection leading to the S-0 or to the isomerization product (K intermediate) are discussed in the framework of the proposed model.},
	isbn = {0027-8424},
	doi = {10.1073/pnas.141220198},
	author = {Logunov, Stephan L. and Volkov, V. V. and Braun, Markus and El-Sayed, Mostafa A}
}
@article {1224,
	title = {The {\textquoteright}lightning{\textquoteright} gold nanorods: fluorescence enhancement of over a million compared to the gold metal},
	journal = {Chemical Physics Letters},
	volume = {317},
	number = {6},
	year = {2000},
	note = {Mohamed, MB Volkov, V Link, S El-Sayed, MA},
	month = {Feb},
	pages = {517-523},
	abstract = {Gold nanorods capped with micelles and having an aspect ratio of 2.0-5.4 are found to fluoresce with a quantum yield which is over a million times that of the metal. For rods of the same width, the yield is found to increase quadratically while the wavelength maximum increases linearly with the length. We assign this emission to the electron and hole interband recombination. The increase in the emission yield results from the enhancement effect of the incoming and outgoing electric fields via coupling to the surface plasmon resonance in the rods. This is similar to the previously proposed fluorescence and the Raman enhancement on noble metal rough surfaces. (C) 2000 Published by Elsevier Science B.V. All rights reserved.},
	isbn = {0009-2614},
	doi = {10.1016/s0009-2614(99)01414-1},
	author = {Mohamed, MB and Volkov, V. V. and Link, Stephan and El-Sayed, Mostafa A}
}
@article {864,
	title = {Optical rotation of the second harmonic radiation from retinal in bacteriorhodopsin monomers in Langmuir-Blodgett film: evidence for nonplanar retinal structure.},
	journal = {Biophysical journal},
	volume = {73},
	year = {1997},
	month = {1997 Dec},
	pages = {3164-70},
	abstract = {We observed optical rotation of the plane of polarization of the second harmonic (SH) radiation at 532 nm (in resonance with the retinal absorption) generated in reflection geometry in Langmuir-Blodgett film of bacteriorhodopsin (bR). The analysis of the experimental data showed that this effect arises from the nonvanishing contribution of the antisymmetrical part of the hyperpolarizability tensor. This requires that the dipole moment of the resonant electronic transition, the change of the dipole moment upon electronic excitation, and the long axis of the retinal not be coplanar. Such conditions are satisfied only if the retinal has a nonplanar geometry, a conclusion that could lend support to the heterogeneity model of the origin of the biphasic band shape of the linear CD spectrum of the retinal in bR. On the basis of our theoretical analysis, we were able to estimate the angle between the induced dipole moment and the plan that contains the long axis of the chromophore and the transition dipole moment of the retinal absorption.},
	keywords = {Bacteriorhodopsins, Biophysical Phenomena, Biophysics, Circular Dichroism, Molecular Structure, Optics and Photonics, Retinaldehyde, Spectrophotometry},
	issn = {0006-3495},
	doi = {10.1016/S0006-3495(97)78342-5},
	author = {Volkov, V. V. and Svirko, Y P and Kamalov, Valey F. and Song, Li and El-Sayed, Mostafa A}
}
