title: Vibrational coherence from the dipyridine complex of bacteriochlorophyll a: intramolecular modes in the 10-220-cm(-1) regime, intermolecular solvent modes, and relevance to photosynthesis.
abstract: We present the first observations of vibrational coherence in the 10-220-cm-1 region from bacteriochlorophyll a (BChl) in solution. A distinction can be made for the first time between BChl's intramolecular normal modes and intermolecular modes between BChl and solvent. The results show that the low-frequency vibrations that accompany the initial electron-transfer reaction from the paired BChl primary electron donor, P, in photosynthetic reaction centers arise predominantly from intramolecular modes of histidine-ligated BChl macrocycles. The results also suggest that polar-solvent interactions can significantly perturb the electronic properties of BChl in a manner that might have important functional consequences.
mesh_terms: D025541:Bacteriochlorophyll A / Q000737:chemistry* / Q000378:metabolism; D005583:Fourier Analysis; D010788:Photosynthesis; D011725:Pyridines / Q000737:chemistry; D013057:Spectrum Analysis / Q000379:methods
chemical_list: D025541:Bacteriochlorophyll A; D011725:Pyridines; C023666:pyridine