The third order hyperpolarizability, <γ>, of the ground state S0 of bacteriochlorophyll a (BChla) has been determined using degenerate four wave mixing. The <γ> for BChl a in vivo (the B875 and B850 arrays of light harvesting proteins) is enhanced relative to that in vitro (THF). A significantly higher <γ> in B875 than that in B850 suggests stronger pigment interactions in the former resulting from superior overlap of adjacent macrocycles. In addition, a 50-160 fold increase in <γ> for the S1 excited state of relative to S0 of BChl a in vivo provides an alternative method for probing excited state dynamics and a potential application for molecular switching.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry