Numerical study of induced polarization dynamics in ultrafast spectral hole-burning experiments

Abstract

We develop a theoretical description of time and frequency resolved transient spectroscopy in non-collinear geometry in a more complete way in respect to the interaction between the applied electric fields and the induced population changes in the sample. For this purpose we deduce a set of differential equations considering a vibrational mode exhibiting finite phase relaxation and an inhomogeneous broadening with cross-relaxation and rotation of the molecules with an average rotation time. In order to describe the electric fields according to experimental conditions a different chirp of the two fields is included in the model as well as calculation of probing components parallel and perpendicular in respect to the excitation. The coherent interaction is solely seen in the parallel probing signal. A time dependent evolution of the transient spectral hole is inferred from the calculations, strongly influenced by phase relaxation. Experimental data on diluted methanol with excitation of the OH-stretching mode demonstrates a temporal evolution of the transient hole in accordance to the calculations.