VIBRATIONAL DEACTIVATION OF N-2(V=1) BY INELASTIC-COLLISIONS WITH HE-3 AND HE-4 - AN EXPERIMENTAL AND A THEORETICAL-STUDY

A new N-2-He intermolecular potential with vibrational coordinate depe ndence is presented. Rate constants for the vibrational deactivation o f N-2(v = 1) by He in the gas phase have been calculated over the temp erature range 5-300 K, Accurate values of the rate constants for this process are known down to 100 K. We have now extended these measuremen ts down to 70 K for the deactivation of N-14(2)(v = 1) by He-4 and dow n to 50 K for the deactivation of N-15(2)(v = 1) by He. Agreement betw een the theoretically calculated and the experimentally determined rat e constants is excellent with the calculated values reproducing the ex perimental measurements within their error bars. An investigation of t he low impact energy regime is also presented. While this focuses on c ollision energies of less than 20cm(-1) and yields rate constants whic h are in a temperature region inaccessible to our experimental method, it gives further insights into the influence of the attractive well o n vibrational energy transfer processes. (C) 1997 American Institute o f Physics.