Coherent and sequential contributions to femtosecond transient absorption spectra of a rhodamine dye in solution.
A unified description is presented of sequential and coherent contributions to optical transient absorption measured by femtosecond pump-supercontinuum probe spectroscopy. All inherent transient terms are taken into account. The "coherence spike" seen during pump-probe overlap is thereby decomposed into its components. The method is demonstrated with rhodamine 110 in methanol. Pure homogeneous dephasing times are obtained from a simultaneous fit of all pertinent measurements. Vibronic structure in the coherence spectrum is assigned to stimulated Raman scattering between vibrational levels in the first excited electronic state. The time-zero spectrum for stimulated emission and the solvation relaxation function are also obtained.
Dobryakov
A L
AL
Department of Chemistry, Humboldt University, Berlin, Germany. dobr@chemie.hu-berlin.de
Kovalenko
S A
SA
Ernsting
N P
NP