Vibrational dependence, temperature dependence, and prediction of line shape parameters for the H2O-H2 collision system

Robert Gamache, Bastien Vispoel, Candice L. Renaud, Kara Cleghorn, Léna Hartmann

Research output: Contribution to journalArticlepeer-review

Abstract

In a recent work on line shape parameters for the H 2 O-H 2 [Renaud et al., Icarus, 306,275, 2018] it was shown that this far off-resonance collision system displays strong vibrational dependence. In Renaud et al., calculations were made for bands with one bend or stretch (symmetric or antisymmetric) vibrational quanta exchanged. Water is seen throughout the universe under a vast range of conditions. The needs of the spectroscopic and astrophysics communities include data for water vapor transitions with multiple quanta exchanged. In this work, calculations were made using the Modified Complex Robert-Bonamy (MCRB) formalism for 0–4 vibrational quanta exchanged in the ν 1 , ν 2 , and ν 3 bands, and the 3ν 1 + ν 3 band at 13 temperatures from 200 to 3000 K: calculations for more than 100,000 transitions. From these data, the vibrational dependence of the half-width, line shift, and their temperature dependence are studied as a function of rotational transition. The results show a strong and unusual vibrational dependence. The data were used to develop a prediction routine, which is based on theory [Gamache and Hartmann, JQSRT, 83, 119, 2004] rather than ad hoc fitting to a polynomial or other forms. The resulting prediction algorithm gives line shape parameters with much lower uncertainty compared to those from J″ average values or polynomial methods. A line file, based on HITRAN2016, was created for remote sensing applications that study H 2 O in hydrogen-rich atmospheres.

Original languageEnglish
Pages (from-to)186-196
Number of pages11
JournalIcarus
Volume326
DOIs
Publication statusPublished - 1 Jul 2019
Externally publishedYes

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