title: Control of retinal isomerization in bacteriorhodopsin in the high-intensity regime.
abstract: A learning algorithm was used to manipulate optical pulse shapes and optimize retinal isomerization in bacteriorhodopsin, for excitation levels up to 1.8 x 10(16) photons per square centimeter. Below 1/3 the maximum excitation level, the yield was not sensitive to pulse shape. Above this level the learning algorithm found that a Fourier-transform-limited (TL) pulse maximized the 13-cis population. For this optimal pulse the yield increases linearly with intensity well beyond the saturation of the first excited state. To understand these results we performed systematic searches varying the chirp and energy of the pump pulses while monitoring the isomerization yield. The results are interpreted including the influence of 1-photon and multiphoton transitions. The population dynamics in each intermediate conformation and the final branching ratio between the all-trans and 13-cis isomers are modified by changes in the pulse energy and duration.
authors: Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA.
authors: Andrei C
authors: AC
authors: Florean
authors: David
authors: D
authors: Cardoza
authors: James L
authors: JL
authors: White
authors: J K
authors: JK
authors: Lanyi
authors: Roseanne J
authors: RJ
authors: Sension
authors: Philip H
authors: PH
authors: Bucksbaum
mesh_terms: D000042:Absorption; D001436:Bacteriorhodopsins / Q000737:chemistry*; D019617:Halobacterium salinarum / Q000737:chemistry*; D007536:Isomerism; D008027:Light; D012172:Retinaldehyde / Q000737:chemistry*; D013057:Spectrum Analysis
chemical_list: D001436:Bacteriorhodopsins; D012172:Retinaldehyde