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EXCITED STATE BEHAVIOR OF PHYTOCHROME P r
Author(s) -
Teuchner Klaus,
Schulz Michael,
Stiel Holger,
Maisch Manfred,
Rudiger Wolfhart
Publication year - 1995
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1995.tb02411.x
Subject(s) - excited state , picosecond , femtosecond , absorption (acoustics) , phytochrome , excitation , atomic physics , ground state , relaxation (psychology) , absorption cross section , chemistry , physics , optics , laser , cross section (physics) , psychology , social psychology , red light , botany , quantum mechanics , biology
The primary excited state processes of phytochrome, the plant chromoprotein responsible for most photomorphogenetic responses, are investigated by picosecond intensity‐dependent transmission measurements. At sufficient high excitation intensity (starting at photon flux densities of about 1′10 25 cm −2 s −l ) a moderate bleaching of the absorption is observed. For the quantitative analysis of the experimental data a rate equation system approach for the energy levels responsible for the ultrafast transformation P r → lumi‐R and the photon transport through the sample was utilized. The following was found for the excited state parameters of the phytochrome P r : (1) an excited state absorption of the same order of magnitude as the ground state absorption (cross section: S̀ exc = 4′10 −16 cm −2 at 650 nm), (2) a fast relaxation of the higher excited singlet state on the femtosecond time scale.