N2-, O2- and He-collision-induced broadening of sulfur dioxide ro-vibrational lines in the 9.2 micron atmospheric window

Year: 2014

Authors: Tasinato N., Charmet AP., Stoppa P., Giorgianni S., Buffa G.

Autors Affiliation: Univ Ca Foscari Venezia, Dipartimento Sci Mol & Nanosistemi, I-30123 Venice, Italy; INO CNR, I-56127 Pisa, Italy; Univ Pisa, Dipartimento Fis E Fermi, I-56127 Pisa, Italy.

Abstract: Sulfur dioxide (SO2) is a molecule of considerable interest for both atmospheric chemistry and astrophysics. In the Earth’s atmosphere, it enters in the sulfur cycle and it is ubiquitous present in polluted atmospheres, where it is responsible for acid rains. It is also of astrophysical and planetological importance, being present on Venus and in interstellar clouds. In this work the collisional broadening of a number of nu(1) ro-vibrational lines of SO2 perturbed by N-2, O-2 and He are investigated at room temperature in the 9 mu m atmospheric region by means of high resolution tunable diode laser (TDL) infrared spectroscopy. From N-2- and O-2-broadening coefficients, the broadening parameters of sulfur dioxide in air, useful for atmospheric applications, are derived as well. From the present measurements some conclusions on the quantum number dependence of the N-2-, O-2- and He-broadening coefficients are drawn. While the J dependence is weak for all the perturbers investigated, different trends with K-a are reported. N-2-broadening coefficients show a slight decrease with increasing values of K-a, whereas O-2 and He broadening cross sections first increase up to K-a ’’ approximate to 6 and then they keep a nearly constant value. A comparison and a brief discussion on the efficiency of self-, N-2-, O-2- and He-collisional dynamics are given. The data obtained represent a significant analysis on foreign broadening of SO2 useful for atmospheric remote sensing and astrophysical applications.

Journal/Review: SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY

Volume: 118      Pages from: 373  to: 379

More Information: This work has been financially supported by MIUR (PRIN 2009 funds for project: Molecular Spectroscopy for Atmospherical and Astrochemical Research: Experiment, Theory and Applications), and by University Ca’ Foscari Venezia (FRA funds). N.T. thanks University Ca’ Foscari Venezia for his post-doctoral position.
KeyWords: Sulfur dioxide; Foreign broadening coefficients; Collisional cross sections; TDL spectroscopy; N-2, O-2, He broadening
DOI: 10.1016/j.saa.2013.08.071

Citations: 20
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