The initial photochemistry of vision

Ming Yan, R. R. Alfano, L. Rothberg, T. M. Jedju, D. Manor, G. Weng, R. Callender

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The 11-cis to 11-trans torsional isomerization of retinal chromophore in rhodopsin has long been known to be involved in the early photochemistry of visual process [1]. Recent work on generation of femtosecond pulses in blue-green region of spectrum made it possible to study this process directly. We have done time-resolved absorption experiments on rhodopsin in both protonated and deuterated aqueous environments at room temperature [2, 3]. These measurements test both the standard picture of rapid photoisomerization and also address the issue of whether proton translocation is also important in the initial step of vision [4]. A 500 nm 150 fs pump pulse initiates die reaction and a white light continuum probe is used to monitor absorbance transients in the 500 to 640 nm range. We observed two distinct kinetic components having 200 fs and 3 ps lifetimes. These data are well modeled by rate equations based on scheme depicted in Figure 1 which illustrates isomerization along the torsional coordinate of the 11-cis bond of the retinal chromophore. As illustrated, the 200 fs time can be associated with the appearance of a 90 degree twisted metastable intermediate by rotation around the double bond on the excited state surface and the 3 ps time with the decay of that intermediate to form the fully isomerized all-trans photoproduct known as bathorhodopsin. These times as well as the absorption spectrum (Figure 3) of the twisted metastable configuration agree well with the semiempirical energy level and molecular dynamics calculations of Tallent et al.[5].

Original languageEnglish (US)
Title of host publicationLEOS 1992 - Conference Proceedings, IEEE Lasers and Electro-Optics Society Annual Meeting
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages2
ISBN (Electronic)0780305264
StatePublished - 1992
Externally publishedYes
Event1992 Annual Meeting of the IEEE Lasers and Electro-Optics Society, LEOS 1992 - Boston, United States
Duration: Nov 16 1992Nov 19 1992

Publication series

NameConference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS
ISSN (Print)1092-8081


Conference1992 Annual Meeting of the IEEE Lasers and Electro-Optics Society, LEOS 1992
Country/TerritoryUnited States

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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