Buffer-gas effect on the rotovibrational line intensity distribution: Analysis of possible mechanisms
Institute of Physics, Saint Petersburg State University, Peterhof,
Saint Petersburg 198904, Russia
Published online: 15 October 2000
Line intensities Am (|m| ≤ 4) of the HF fundamental band (T=293 K) are found to decrease linearly with the buffer-gas (Xe) density (DXe = 2.6-16 Amagat). The obtained slopes Δ1(m) of the Am(d)/ Am(0) vs. dXe plots are maximum at |m| =1 (Δ1(1) ≈ Δ1(-1) = 1.7(4) * 10-2Amagat-1) and rapidly drop with |m| . Many possible mechanisms are considered; the most effective one appears to be the HF-Xe bimer formation, with the equilibrium constant strongly depending on the rotational quantum number. The rigid-rotator approximation used gives the density derivatives considerably smaller than the measured ones. The disbalance may be lessened for vibrating rotators by allowance for the interband intensity transfer induced by the vibrational modulation of short-range forces.
PACS: 33.20.Ea – Infrared spectra / 33.70.-w – Intensities and shapes of molecular spectral lines and bands / 34.10.+x – General theories and models of atomic and molecular collisions and interactions (including statistical theories, transition state, stochastic and trajectory models, etc.)
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2000