Delayed New Date TBD - Ultrafast transient absorption revisited: Watching molecular vibrations in photosynthetic light-harvesting complexes

Date: 
Monday, December 1, 2014 -
2:00pm to 3:00pm
Speaker: 
Jeffrey Cina
Speaker's Institution: 
University of Oregon

Molecular vibrations, along with the motion of protein- or solvent-host atoms, are known to exert important influence over the time-course of electronic excitation transfer in both model complexes and photosynthetic light-harvesting antennas. The spatial transport of electronic excitation energy has been investigated by numerous labs in recent years with a wide variety of ultrafast electronic spectroscopic measurements, including two-dimensional electronic spectroscopy, time-resolved fluorescence anisotropy, and spectrally-resolved ultrafast transient absorption. New experiments on the antennas of cryptophyte algae by Gregory Scholes and co-workers [S. D. McClure, D. B. Turner, P. C. Arpin, T. Mirkovic, and G. D. Scholes, "Coherent Oscillations in the PC577 Cryptophyte Antenna Occur in the Excited Electronic State," J. Phys. Chem. B 118, 1296−1308 (2014)] using the last of these techniques, have revealed oscillatory quantum beats associated with a large number of vibrational modes weakly coupled to the electronic degrees of freedom. In this talk, I will present initial findings of a collaborative theoretical project with the Scholes group aimed at elucidating some of the key features of their data.