Quantum Number Dependence of Lineshift Coefficients Induced by Collisions with Noble Gas Perturbers in the ν3 Band of NO2

Abstract

To complete our study concerning lineshift in the rovibrational spectrum of 14N16O2, a pulse-driven three-channel lead salt diode laser spectrometer was applied to record high-resolution spectra at room temperature in the 6.2-μm region corresponding to the ν3 band at low NO2 concentrations. The shift was studied for collisions with the noble gases He, Ne, Ar, Kr, and Xe. This paper extends our recently published data in order to analyze the quantum number dependence of the shift effect more precisely. Therefore, in this paper, additionally eight unresolved NO2 doublets covering an enlarged quantum number range (10 ≤ N″ ≤ 34, 2 ≤ K″a ≤ 6) were studied. For all doublets, shift coefficients δNO2–noble gas and additionally broadening coefficients γNO2–noble gas were determined. Hereby, the experimental data confirm general trends published recently. In this study, in the case of broadening for the lighter rare gases helium, neon, and argon, only a slight decrease of γNO2–noble gas was observed, whereas for the rare gases with a higher atomic weight, i.e., krypton and xenon, a pronounced decrease of γNO2–noble gas with increasing rotational quantum number N″ occurred. All measured lineshift coefficients were negative. The absolute value of the determined lineshift coefficient ‖δNO2–noble gas‖ increases with the mass of the noble gas perturber, i.e., ‖δNO2–He‖ < ‖δNO2–Ne‖ < ‖δNO2–Ar‖ < ‖δNO2–Kr‖ < ‖δNO2–Xe‖. Within the studied quantum number range, an increase ‖δNO2–noble gas‖ with increase of N″ was observed. A typical trend of the shift and broadening data on the quantum number K″a was not observed.