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Picosecond Kinetics of Excited State Relaxation in Biliverdin Dimethyl Ester
Author(s) -
Holzwarth Alfre D.,
Wendler Joachim,
Schaffner Kurt,
Sundström Villy,
Sandström Ake,
Gillbro Tomas
Publication year - 1983
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.198300032
Subject(s) - chemistry , picosecond , relaxation (psychology) , nanosecond , biliverdin , excited state , photochemistry , kinetics , vibrational energy relaxation , fluorescence , organic chemistry , molecule , atomic physics , psychology , laser , heme , optics , enzyme , social psychology , physics , heme oxygenase , quantum mechanics
The relaxation processes of biliverdin IXα dimethyl ester have been studied by time‐resolved absorption and fluorescence detection, using pump‐probe and single‐photon timing techniques, respectively. The results complement and extend those of earlier investigations. 1,3–5 In 2‐methyltetrahydrofuran, chloroform, ethanol, and ethyl lactate, four emitting species, two short‐lived (picosecond) and two long‐lived ones (nanosecond), have been detected. In methanol, the number of emitters is possibly reduced to three. In the cases of four emitters, these can be attributed to either three or four ground state forms. We conclude that the radiationless relaxation of the short‐lived excited states is simultaneously induced both by proton transfer processes and by conformational changes, as previously discussed. 3 The spectroscopic properties of the long‐lived species point to the presence of relatively rigid conformations of the bilatriene in liquid solutions at room temperature. The possible relevance of this observation with regard to the influence of protein interactions on the conformational equilibrium of tetrapyrroles in phycobiliproteins is discussed.