Vibrational dissipation and dephasing of I2(v = 1–19) in solid Kr

Abstract

Time- and frequency-resolved coherent anti-Stokes Raman scattering is used to carry out systematic measurements of vibrational dephasing on I₂(v = 1–19) isolated in solid Kr, as a function of temperature, T = 7–45 K. The observed quantum beats, ω_v′,v″ allow an accurate reconstruction of the solvated molecular potential, which is well represented by the Morse form: ω_e = 211.56 ± 0.14, ω_ex_e = 0.658 ± 0.006. Near T = 7 K, the coherence decay rates γ_v,0 become independent of temperature and show a linear v-dependence, indicative of dissipation, which must be accompanied by the simultaneous creation of at least four phonons. At higher temperatures, the T-dependence is exponential and the v-dependence is quadratic, characteristic of pure dephasing via pseudo-local phonons. A normal mode analysis suggests librations as the principle modes responsible for pure dephasing.