Catalytic Efficiencies of H2O, D2O, NO, and HCl in the Vibrational Relaxation of HF and DF

Abstract

The catalytic efficiencies of H20, D20, NO, and HCI in the vibrational relaxation of HF and of NO in the vibrational relaxation of DF were investigated over the temperature and total pressure ranges of 1000 to 4100 0 K and 0.1 to 0.3 atm, respectively. Measurements were made in an Ar diluent behind incident shock waves. The extent of vibrational excitation in HF was determined as a function of time by continuously monitoring the infrared emission intensity at 4150±200 em-I. Water appears to relax HF principally by means of a direct transfer of vibrational energy (V-V) between the collision partners. Furthermore, its collisional efficiency was found to be in fair agreement with the results reported by others for the analogous process of HCI relaxation by H20. Nitric oxide was found to be at least an order-ofmagnitude more efficient as a collision partner in the vibrational relaxation of HF than is known for either of the molecules N2 or O2. A small amount of data regarding the effect of HCI upon the vibrational relaxation of HF was collected. Within the temperature range considered, its catalytic efficiency was found to be comparable to that of HF itself.

The relaxation of OH (v = 1) and OD (v = 1) by H2O and D2O at temperatures from 251 to 390 K

“…In particular, such forces were invoked in the 1970s to explain the rapid rates observed for the vibrational relaxation of HF(v = 1) both in HF-HF collisions 8,9 and in collisions with H 2 O. 8b, [9][10][11] In such cases, it is less likely that IVR in any complex that is formed will occur faster than re-dissociation to the collision partners in their original vibrational states. Consequently, the mechanism for vibrational relaxation must take account of the competition between IVR in the complex and its re-dissociation without loss of the initial vibrational excitation.…”

Quantum Dynamics of Rotational Energy Transfer Processes for N2–HF and N2–DF Systems

“…ν 2 ranges from 1 to 7 for HF − and from 1 to 5 for DF. ,,− In particular, Yang et al showed the importance of near energy resonant vibration–rotation (V–R) channels in the relaxation processes of vibrationally excited HF by N 2 . These experimental data indicated that the vibrational energy transfer rate coefficients (∼10 –15 cm 3 s –1 mol –1 ) are much smaller than those of other systems in which the HF molecule participates, such as H 2 –HF (∼10 –12 cm 3 s –1 mol –1 ), H 2 O–HF (∼10 –10 cm 3 s –1 mol –1 ), ,, and HF–HF (∼10 –11 cm 3 s –1 mol –1 ) . Owing to complexity and difficulty of direct measurements, the rotationally resolved rate coefficients for both systems have not been reported.…”