Line-by-line spectroscopic parameters of HFC-32 ro-vibrational transitions within the atmospheric window around 8.2 μm

Abstract

Difluoromethane (CH2F2,HFC-32) presents strong ro-vibrational bands within the 8–12 μm atmospheric window and hence it represents a greenhouse gas able of contributing to global warming. Numerous spectroscopic studies have been devoted to this molecule, however, much information on line-by-line parameters, like line intensities and broadening parameters, is still lacking. In this work, line-by-line spectroscopic parameters are retrieved for several CH2F2 ro-vibrational transitions belonging to the ν7 band located around 8.5 μm. Self-broadening as well N2– and O2– broadening experiments are carried out at room temperature by using a tunable diode laser (TDL) spectrometer. The line shape analysis of CH2F2 self-broadened spectra leads to the determination of resonant frequencies, integrated absorption coefficients and self-broadening parameters, while CH2F2–N2 and CH2F2–O2 broadening coefficients are obtained from foreign-broadening measurements. In addition, the broadening parameters of CH2F2 in air are derived from the N2– and O2– broadening coefficients. The results of the present work provide fundamental information to measure the concentration profiles of this molecule in the atmosphere through remote sensing spectroscopic techniques.