Premium
Dipole Strengths of the Q y (0,0) Bacteriochlorophyll c Transition ¶
Author(s) -
Bartczak Adam,
Dudkowiak Alina,
Frackowiak Danuta
Publication year - 2003
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 - 10.1562/0031-8655(2003)0780525dsotqb2.0.co2
Subject(s) - bacteriochlorophyll , dipole , transition (genetics) , chemistry , physics , organic chemistry , biochemistry , gene , pigment
The absorption spectra of bacteriochlorophyll (BChl) c solutions in two mixtures of two solvents (acetonitrile with pyridine and dimethylsulfoxide with methanol) exhibiting different refractive indices were measured and deconvoluted into Gaussian components. The refractive index of mixed solvents was changed by the change in the ratio of the volumes of the liquids used in the mixture. Using the Q y (0,0) band half widths and absorption coefficient, based on the simplified formula proposed by Knox, the dipole strengths of the Q y (0,0) BChl c transition for various values of solvent refractive index were calculated and compared with values given by Knox and Spring. For both investigated combinations of two liquids, the dependence of Q y (0,0) transition dipole strength of the BChl c on solvent refractive index was almost linear. The slopes of the lines obtained from the experimental absorption bands were different for two investigated solvent mixtures. More accurate linear dependence and similar slopes of lines for both solvent mixtures were obtained using half widths and absorption coefficients of the Gaussian components of Q y (0,0) transition. It is explained by the superposition of the contributions from other electronic and vibronic transitions of BChl c monomers or possibly also from transitions of the pigments involved in some complexes with solvent molecules in the absorption region investigated. The results show that the formula proposed by Knox can be successfully applied also for BChl c , after elimination of the overlapped contributions from the other transitions, by applying Gaussian analysis to select only contribution from Q y (0,0) pigment transition.