Mid-infrared spectrum of the weakly bound complex CO₂–SO₂

Abstract

The mid-infrared spectrum of the CO₂–SO₂ van der Waals complex was measured near the R(0) transition of the asymmetric stretch of the CO₂ monomer at 2349.917 cm⁻¹. The spectra were recorded using a molecular beam tunable diode laser spectrometer, in which the injection nozzle was mounted in a position axial to the Herriott multipass cell. The transitions are c-type, in agreement with spin statistical analysis. Transitions originating from levels with odd K_a in the vibrational ground state are absent from the spectrum. The main spectroscopic constants are ν₀ = 2349.6159(1) cm⁻¹, A″ = 5544.98(40) MHz, B″ = 1510.034(37) MHz, C″ = 1489.402(36) MHz,  = 4.578(16) kHz, A′ = 5524.58(63) MHz, B′ = 1508.28(14) MHz, C′ = 1488.42(21) MHz, and  = 4.07(78) kHz. The spectral assignment was confirmed by microwave-infrared double resonance experiments using several known a-type microwave transitions of the complex.

Acknowledgements

This work was made possible by the financial support of the Natural Sciences and Engineering Research Council of Canada (NSERC). HDO gratefully acknowledges graduate scholarships from NSERC and Alberta Ingenuity. The authors thank Yunjie Xu for useful discussions.