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Proceedings Paper

Nonlinear absorbance effects in bacteriorhodopsin
Author(s): George W. Rayfield
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Paper Abstract

Bacteriorhodopsin (BR) is a protein found in the cell membrane wall of Halobacterium halobium and serves as a light-activated proton pump (i.e., the protein converts light energy into chemical energy). The chromophore (retinal) responsible for light absorption is located within a pocket of the opsin and is bound via a Schiff base to a lysine residue in the amino acid sequence. When BR is illuminated by a laser light flash, transient changes occur in the visible absorption spectrum of the protein -- i.e., the material is photochromic. The optical absorption changes are characterized by a series of photointermediates, with characteristic rise and fall times that range from less than a picosecond to more then 10 milliseconds. This photochromic property of BR makes it a useful material for optical devices. With an aim toward developing an optical switch for the Army, we are studying the transient absorption of nanosecond light pulses from a dye laser in the spectral region in which the absorbance of BR increases as light intensity increases. This nonlinear effect is wavelength-dependent and becomes a bleach in a different spectral window. The nonlinear absorption change is reversible.

Paper Details

Date Published: 1 March 1991
PDF: 10 pages
Proc. SPIE 1436, Photochemistry and Photoelectrochemistry of Organic and Inorganic Molecular Thin Films, (1 March 1991); doi: 10.1117/12.45121
Show Author Affiliations
George W. Rayfield, Bend Research, Inc. (United States)


Published in SPIE Proceedings Vol. 1436:
Photochemistry and Photoelectrochemistry of Organic and Inorganic Molecular Thin Films
Marcus F. Lawrence; Arthur Jesse Frank; S. Ramasesha; Carl C. Wamser, Editor(s)

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