Time-resolved sub-picosecond Raman spectroscopy for investigating fast nonequilibrium dynamics

Abstract

With the rapid development of short-pulse optical technology and sensitive multi-channel optical detectors, it has been possible to use time-resolved sub-picosecond Raman spectroscopy to study the non-equilibrium dynamics of ionic excitations in condensed matter, both in the electronic ground state and in an electronic excited state. The time-resolved study of the ‘hot’ transverse-optic mode in diamond is an example of very early work in the field, with piccosecond resolution. The theory of the pump-probe excited-state Raman scattering technique to investigate the dynamics of the ionic as well as electronic excitations is presented. Experimental results, particularly related to the dynamics of hot LO-phonons generated by photo excited carriers in GaAs and other similar III-V semiconductors, are discussed to show the importance of the technique.