Vibrational energy transfer in N2-N2 collisions:: A new semiclassical study -: art. no. 174315

The vibrational energy relaxation in collisions between N(2) molecules in the low- and medium-lying vibrationally excited levels was revisited using the semiclassical coupled-state method and the use of two different potential-energy surfaces having the same short-range potential recently determined from ab initio calculations but with different long-range interactions. Compared to the data reported in the classical work by Billing and Fisher [Chem. Phys. 43, 395 (1979)], the newly calculated vibration-to-translation rate constant K(1,0 vertical bar 0,0) is in much better agreement with the available experimental data over a large temperature interval, from T = 200 K up to T = 6000 K. Nevertheless, as far as the vibration-to-translation exchanges are concerned, the lower-temperature regime remains quite critical in that the new rate constants do not completely account for the rate constant curvature suggested by the experiments for temperatures lower than T = 500 K. The dependence of the state-selected vibration-to-vibration rate constants, K(nu, nu-Delta nu vertical bar 0,1), both upon the vibrational quantum number v and the gas temperature are calculated. The substantial deviations from previously found behaviors could have major consequences for the vibrational kinetic modeling of N(2)-containing gas mixtures. (c) 2005 American Institute of Physics.