Abstract

The interpretation of vibrational lineshapes in liquids has been the subject of numerous experimental and theoretical studies. Dephasing processes are crucial for the interpretation of optical processes in condensed phases. These processes are traditionally classified as either homogeneous or inhomogeneous. When different molecules have different transition frequencies because of varying local environments or initial states, the spectral lineshape is said to be inhomogeneously broadened. This broadening carries no dynamical information. Homogeneous broadening arises from an interaction with a bath with a very fast time scale, causing rapid fluctuations in the local environment. Since nuclear motions in liquids cover a broad range of time scales, it is not clear whether spectral lineshapes can be classified as either homogeneous or inhomogeneous. Even when such classification is possible by virtue of separation of timescales, it is not easy to firmly establish it experimentally.

© 1994 Optical Society of America