Coherent rovibrational revivals in a thermal molecular ensemble

Abstract

We report an experimental and theoretical study of the evolution of vibrational coherence in a thermal ensemble of nitrogen molecules. Rotational dephasing and rephasing of the vibrational coherence is detected by coherent anti-Stokes Raman scattering. The existence of ro-vibrational coupling and the discrete energy spectrum of the rotational bath lead to a whole new class of full and fractional ro-vibrational revivals. Following the rich ro-vibrational dynamics on a nanosecond time scale with sub-picosecond time resolution enables us to determine the second-order ro-vibrational constant γe and assess new possibilities of controlling decoherence.

Hybrid fs/ps coherent anti-Stokes Raman scattering for multiparameter measurements of combustion and nonequilibrium

“…8.1(b) is a result of the unequal spacing of the interfering transitions. The regions of constructive interference are referred to as rovibrational revivals [219,149,75] and their origin will be discussed in the next section. Because these revivals offer increased sensitivity to temperature and pressure under certain measurement conditions, it is of interest to investigate them further.…”

“…A revival time can be defined for two nearby rotational states as the first occurrence of constructive interference between them. In other words, the rovibrational revival occurs when molecules in nearby rotational states are vibrating in phase [149]. The revival time, or the time for two oscillators to reach a 2π phase shift, is a function of the frequency difference between the two transitions.…”

“…The revival time, or the time for two oscillators to reach a 2π phase shift, is a function of the frequency difference between the two transitions. Any two transitions within the probe bandwidth will contribute to revivals, thus the revival time previously defined [75,149] can be modified to describe two specific states. The difference in two nearby Q-branch transitions (∆ω) can be written as Eq.…”