Line parameters measurements and modeling for the ν6 band of CH3I: A complete line list for atmospheric databases

Abstract

The present work is dedicated to the ν6 band of 12CH3I with the aim of generating a complete line list for databases. High resolution Fourier transform spectra have been recorded in MONARIS and a multispectrum fitting procedure using Voigt profile has been applied to retrieve line positions, intensities, and self-broadening coefficients for around 1200 transitions of the ν6 band between 854 and 963 cm−1. Rotational dependences of transition dipole moment squared and self-widths have been studied and empirically modeled. Line positions are retrieved with accuracy equal to 4.10−4 cm−1. The accuracy of line intensities and self-widths measurements is estimated between 5 and 10 %. Theoretical estimates of CH3I self-broadening coefficients for large ranges of rotational quantum numbers (0 ≤ J ≤ 70, 0 ≤ K ≤ 20) are also provided in the frame of a semi-classical approach with exact trajectories and of a semi-empirical method including a correction factor to the Anderson-type line-width expression. Comparisons of our results with the data previously published in the literature are presented and discussed. A complete line list of 5787 transitions is generated. Available as supplementary material, this line list can be used for spectroscopic databases and atmospheric or industrial detection of CH3I.