In this work, we demonstrate the use of broad-band pump-probe spectroscopy to measure femtosecond solvation dynamics. We report studies of a rhodamine dye in methanol and cryptophyte algae light-harvesting proteins in aqueous suspension. Broad-band impulsive excitation generates a vibrational wavepacket that oscillates on the excited-state potential energy surface, destructively interfering with itself at the minimum of the surface. This destructive interference gives rise to a node at a certain probe wavelength that varies with time. This reveals the Gibbs free-energy changes of the excited-state potential energy surface, which equates to the solvation time correlation function. This method captures the inertial solvent response of water (∼40 fs) and the bimodal inertial response of methanol (∼40 and ∼150 fs) and reveals how protein-buried chromophores are sensitive to the solvent dynamics inside and outside of the protein environment.
|Number of pages||10|
|Journal||Journal of Physical Chemistry Letters|
|State||Published - Nov 17 2016|
Bibliographical noteFunding Information:
C.C.J. is supported by the Natural Science & Engineering Research Council. This work was supported by the Natural Sciences and Engineering Research Council of Canada and the United States Air Force Office of Scientific Research (FA9550- 13-1-0005). P.A.K. and J.A.C. were supported in part by National Science Foundation Grant CHE-1213406.
© 2016 American Chemical Society.
ASJC Scopus subject areas
- Materials Science (all)
- Physical and Theoretical Chemistry