The Roles of the S1 and S2 Scattering Matrix Terms on Half-Widths and Their Temperature Dependence for the Water Vapor-Nitrogen System

• Main Authors: Gamache, R R, Antony, B K, Gamache, P R, Hartmann, Jean-Michel
• Format: Conference Proceeding
• Language: English
• ISSN: 0094-243X
• DOI: 10.1063/1.2402789

The effect of the first (S1) and second (S2) order successive approximations to the S matrix on the half-width and the temperature dependence of the half-width are studied for the water vapor-nitrogen system. The calculations are done via the Robert-Bonamy semi-classical formalism. It is found that the influence of the S1 and S2 terms depends on the rotational states of the transition. For the H2O-N2 system, half-widths for H2O transitions with low J quantum numbers are dominated by the S2 terms. Transitions with high J values the half-width is determined largely by the S1 term. For transitions with intermediate values of J both the S1 and S2 terms contribute. The temperature dependence of the half-width also depends on whether it is the S2, S1 or S2+S1 that are contributing to the half-width. It is found that the standard power law temperature dependence of the half-width is only valid for transitions where Re(S2) dominates. When S1 dominates the temperature dependence is negative and when both terms contribute the temperature dependence is not modeled by the power law.