CO2-CO2 and CO2-Ar continua at millimeter wavelengths

Broadband spectra of the continuum absorption in pure CO2 gas and its mixture with Ar are studied at room temperature using a resonator spectrometer within 105-240 GHz. The expected pressure and frequency dependence is observed. The obtained data are validated by two independent calculations of the interaction-induced absorption using a semiclassical trajectory-based method. The observed continuum is interpreted in terms of bimolecular absorption, including a significant contribution from true bound dimers. A simplified formula describing both frequency and temperature dependency of the CO2-Ar continuum within a frequency range from 60 GHz to 450 GHz at temperatures from 200 K to 400 K is suggested for use in atmospheric studies. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

In this study, the broadband spectra of the continuum absorption in pure CO2 gas and its mixture with Ar were investigated using a resonator spectrometer operating within the frequency range of 105-240 GHz at room temperature. The pressure and frequency dependence as expected were observed, and the obtained data were validated by two independent calculations. A simplified formula was proposed to describe the frequency and temperature dependency of the CO2-Ar continuum for atmospheric studies, covering a wide frequency range from 60 GHz to 450 GHz at temperatures from 200 K to 400 K.