Multi-laboratory measurements of 12CH4 2ν3 band line parameters. Part I: Line intensities with relative combined standard uncertainties at the permille level

Published

July 5, 2025

Author(s)

Zachary Reed, Manfred Birk, Yan Tan, Christina Cecelski, Georg Wagner, Shui-Ming Hu, David Long, Rui-Heng Yin, Joseph Hodges

Abstract

We present accurate transition intensities for the R0 to R10 manifolds of 12CH4 in the 2ν3 tetradecad region determined independently by two separate laboratories through cavity ring-down spectroscopy and Fourier Transform spectroscopy measurements. Each experiment involved multi-spectrum fits to low-pressure spectra acquired at Doppler-limited conditions which largely eliminated complications from line shape effects caused by collisional broadening and line mixing. Intensities are reported for manifolds and specified multiplets comprising blended transitions, as well as for individual transitions. Summation of the manifold and multiplet intensities agree at the permille level, whereas highly blended individual transitions agree at the several permille level. For measurements of methane, the intensities reported here will enable more accurate spectroscopic determinations of amount-ofsubstance, and will support progress in remote sensing missions and future refinements of its other spectroscopic parameters.

Citation

Journal of Quantitative Spectroscopy and Radiative Transfer

Pub Type

Journals

Keywords

methane, molecular spectroscopy, molecular lineshapes

Citation

Reed, Z. , Birk, M. , Tan, Y. , Cecelski, C. , Wagner, G. , Hu, S. , Long, D. , Yin, R. and Hodges, J. (2025), Multi-laboratory measurements of 12CH4 2ν3 band line parameters. Part I: Line intensities with relative combined standard uncertainties at the permille level, Journal of Quantitative Spectroscopy and Radiative Transfer (Accessed July 25, 2025)