Temperature dependence of vibrational relaxation in the HF–DF, HF–CO2, and DF–CO2 systems. II

Abstract

Measurements of vibrational energy transfer probabilities are presented for the temperature range 205-360'K for HF-DF, HF-CO" and DF-CO, gas mixtures. The present results provide an accurate determination of the inverse temperature dependence of the energy transfer probabilities exhibited by these systems. Large deactivation effects caused by HF (DF) polymers were observed for temperatures below 220'K.

Intermolecular V–V energy transfer in the photodissociation of CO2–HF(v=1)

“…We begin by using the compilation of collisional transfer rates assembled by Dzelzkalns and Kaufman, 54 from which they determined the probability for the process in question to be 0.0036, based upon a Lennard-Jones total collision rate. As shown by the experimental results summarized by Lucht and Cool,53 this rate increases with decreasing temperature, namely as T (Ϫ1. 34) .…”

“…Vibrational energy transfer between HF and CO 2 in full collisions has been studied in great detail [46][47][48][49][50][51][52][53][54] and it is instructive to compare these with the results of the present study. We begin by noting that numerous studies have shown that HF (vϭ1) relaxes collisionally with CO 2 via the V -V process discussed above, namely by coupling to the CO 2 (00 0 1) asymmetric stretching vibrational state.…”

Breakdown of energy transfer gap laws revealed by full-dimensional quantum scattering between HF molecules

“…The result is shown in Fig. 2, together with the available experimental 23–29 and previous theoretical 31,32 data. Our quantum mechanical rate coefficient initially decreases with temperature from 100 to 500 K, but increases slowly with temperature from 500 to 1200 K, with a minimum value of 2.1 × 10 −12 cm 3 s −1 mole −1 at 500 K. The calculated rate coefficient (3.03 × 10 −12 cm 3 s −1 mole −1 ) is in quite good agreement with the experimental result of 3.0 × 10 −12 cm 3 s −1 mole −1 at 200 K, reported by Hancock and Green 23 .…”

“…2Calculated vibrational-resolved (1; 0) → (0; 0) rate coefficient as a function of temperature. The current calculated results are compared with available experimental (denoted as Expt 1 23 , Expt 2 24 , Expt 3 25 , Expt 4 26 , Expt 5 27 , Expt 6 28 , Expt 7 29 , and Expt fitting 22 ) and other theoretical results (Theo 1 31 and Theo 2 32 ). All error bars represent the experimental error…”

“…As a working medium for chemical lasers 21 , vibrational relaxation rates of hydrogen fluoride (HF) are of great interest to laser engineering, because they directly determine populations of HF ro-vibrational levels in the laser cavity 22 . The rate coefficient for self-relaxation of HF from its first excited vibrational state,has been extensively studied experimentally 23–29 . Theoretical understanding has unfortunately lagged behind.…”