Bath Fluctuations from Optical Coherence: Liquids and Proteins

ABsTRAcr The vibrational and optical coherence responses of bacteriochlomphylla (BChla) in solution and within the bacterial reaction centa protein of Rh. Sphaaoides ate reported. Fourier transform analysis of the optically impulsively p q a r a i vibrational coherences of BChla in solution show features in the 350-1ux)cm~ Speceal range while the analogous response of the aaxsny bacterioChlmphyll’s (B) in the F i n exhibit the same features as well as low muency mode^ in the ~ 3 5 O c m ” region. A kinetic analysis of the response in the spectral region associated with B exhibits both prompt decay features and a 2.8ps rise. A dominant vibrational mode is observed in the pumpprobe “ponse of the special pair (p) that is presumably associated with vibrational motion of the dimer. 2pulse echo signals from BChla in solution and from P in the protein both &cay exponentially. The associated homogeneous linewidth obtained for P is in good agreement with low temperature hole burning results.