Multispectrum analysis of 12CH4 from 4100 to 4635cm−1: 1. Self-broadening coefficients (widths and shifts)

Multispectrum analysis of 12CH4 from 4100 to 4635cm−1: II. Air-broadening coefficients (widths and shifts)

“…The experimental set up and related information were presented in the first paper of this series of publications [1]. For the convenience of readers some details are repeated here.…”

“…During the recording of the data, gas sample pressures and temperatures were monitored continuously (see [1]). Six spectra recorded with 99.9% enriched 12 C methane were used to obtain positions, intensities and self-broadened , and m 2 + m 3 near 4543 cm À1 .…”

“…1, the strongest bands above the fundamentals are m 1 + m 4 near 4220 cm À1 , m 3 + m 4 near 4320 cm À1 , and m 2 + m 3 near 4540 cm À1 . In a companion study, we recently reported empirical self-broadened widths and self-induced pressure-shift coefficients for over 1400 transitions belonging to five CH 4 bands between 4100 and 4635 cm À1 : m 2 + 2m 4 , m 1 + m 4 , m 3 + m 4 , 2m 2 + m 4 , and m 2 + m 3 [1]. Descriptions of the octad polyad, energy level symmetries, selection rules and other related details may be found in [1,2] and the references therein.…”

“…As a result, our present study surpasses all previous air-broadening results at room temperature, increasing the number of measured transitions in this spectral region from 740 to over 1000 and the number of bands from three to five. It also encompasses P, Q, and R branch transitions for three combination bands with different vibrational symmetries (see [1]). These accurate air-broadening and air-shift coefficients will support tropospheric remote sensing and guide the development of better theoretical models for widths and shifts of methane transitions.…”

Line broadening coefficient calculations for methane perturbed by nitrogen

“…The subject of infrared line shapes studies for methane is extensively documented from an experimental point of view. Some of the most recent works dealt with measurements in the first four polyads of methane (dyad near 1300 cm −1 , pentad near 3000 cm −1 , octad near 4300 cm −1 and tetradecad near 6000 cm −1 ) [31][32][33][34][35][36][37][38][39][40][41][42][43]. We note that the temperature dependencies of line shape parameters and/or line mixing parameters could be determined in some of these studies.…”