Picosecond dephasing and relaxation in vibronic states of molecules in the condensed phase

Abstract

We demonstrate that picosecond photon-echo and absorption-recovery experiments can be used to determine the elastic and inelastic scattering contribution to the relaxation of vibronic transitions in molecules in solids. For pentacene in naphthalene we find that, up to 14 K, dephasing is only determined by vibrational relaxation. The observed exponential activation of this process is interpreted as a decay of the initial level, via a resonant phonon, into other molecular vibrations.