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RESONANCE RAMAN SPECTRA AND NORMAL MODE DESCRIPTIONS OF A BACTERIOCHLOROPHYLL a MODEL COMPLEX
Author(s) -
Donohoe Robert J.,
Frank Harry A.,
Bocian David F.
Publication year - 1988
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.1751-1097.1988.tb02857.x
Subject(s) - bacteriochlorophyll , raman spectroscopy , chemistry , normal mode , resonance (particle physics) , spectral line , resonance raman spectroscopy , excitation , absorption spectroscopy , molecular physics , absorption (acoustics) , chlorin , nuclear magnetic resonance , atomic physics , photochemistry , physics , optics , vibration , quantum mechanics , porphyrin , organic chemistry , pigment
— Resonance Raman (RR) spectra are reported for the bacteriochlorophyll a (BChl a) model complex, copper methylbacteriopheophorbide a (CuBPheo a). The spectra are acquired at a number of excitation wavelengths in the Q y+ Q x and B regions of the absorption spectrum. The RR data obtained for CuBPheo a are correlated to those previously reported for BChl a. The normal modes of the BChl structure are calculated by using the semiempirical quantum chemistry force field (QCFF/ PI) method of Warshel and Karplus [J. Am. Chem. Soc. 94 ,5612–5625 (1972)]. The vibrational data are used in conjunction with the calculations to obtain a cohesive assignment for the normal modes of BChl a with frequencies between 1100 and 1700 cm ‐1 . The forms of the normal modes of BChl a are predicted to be different both from those of chlorophyll a and from those of porphyrins.