Table of Contents
Laser Chemistry
Volume 19, Issue 1-4, Pages 173-178
http://dx.doi.org/10.1155/1999/97059

Femtosecond Time Resolved Infrared Spectroscopy of the Ethylenic Stretch Vibration During the all-Trans to 13-Cis Isomerization of Bacteriorhodopsin

Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, Berlin D-14195, Germany

Received 20 April 1997

Copyright © 1999 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We report on room temperature infrared transient absorption experiments on Bacteriorhodopsin concerning the early picosecond dynamics of the all trans to 13-cis isomerization of the retinal chromophore. The absorption band of the all-trans chromophore ethylenic stretch vibration bleaches concomitantly to photoexcitation whereas new absorption strength is created redshifted within less than 1 ps. the initial bleach recovers partly according to the non unity quantum yield of the photoisomerization within 2 ps. With a time constant of 3ps the low energy absorption band is downshifled 5–10 cm-1. Thus, vibrational relaxation and cooling processes appear to have ended within a few ps and on the time scale of 20 ps a stationary BR-K difference spectrum is obtained.