Local scaling analysis of state-to-state rotational energy-transfer rates in N2 from direct measurements

Abstract

An analysis of recent rotational energy state-to-state rates data in N2 is achieved by using an exact local equation valid within the energy corrected sudden (ECS) frame. This equation connects the rates belonging to each group of five cross-shaped elements characterized by the rotational quantum numbers {(J,J′), (J,J′+2), (J, J′−2), (J−2,J′), (J+2,J′)}. Such an analysis is free of any assumption on the dependence of the basis rates on the rotational energy. It allows one to perform a study of the local validity of the scaling law and a more direct estimation of the scaling length. Previous ECS studies, only based on the inversion–fitting procedure of line-broadening coefficients, are compared with the present results. It is shown that, in spite of good agreement of these last phenomenological approaches with stimulated Raman profiles for compressed N2 gas, they may be unadapted to describe other physical properties. This point is clearly illustrated by the behavior of the rotational angular momentum correlation function. The origin of such a discrepancy is evidenced and a convenient modification of the adiabaticity correcting factor is introduced. Finally, excellent consistency with available experimental data is obtained.