Motional narrowing of Raman Q branches of linear molecules

Abstract
The v 1 and v 3 Raman Q branch lineshapes of N2O in dilute gas mixtures with Ar disclose unmistakable motional narrowing with increasing Ar density, which at 295 K persists up to the highest pressures studied (∼ 140 atm). This narrowing, together with the measured pressure shifts, provides compelling evidence in favour of an indirect vibrational dephasing mechanism mediated by rotational relaxation. The case for this mechanism in N2O/Ar mixtures is stronger than in pure N2O where arrested collision broadening rather than actual narrowing is observed. Theoretical lineshapes are calculated with the use of the J-scrambling model to describe rotational relaxation due to N2O/Ar collisions; agreement in detail with experimental lineshapes is found.

This publication has 7 references indexed in Scilit: