Microwave absorption coefficients of atmospheric pollutants and constituents

Abstract

Calculations of the transition frequencies and absorption coefficients of microwave rotational transitions are given for a number of atmospheric pollutants and constituents. New measurements of the absorption coefficients are made in the vicinity of 70 GHz. The apparatus •used in these measurements is briefly described. The calculated absorption coefficients are compared with these measurements and with existing measurements at other frequencies where available. Transitions with frequencies up to about 200 GHz are considered for the molecules and radicals so 2 , o 3 , H 2 o, N0 2 , H 2 S, H 2 co, NH 3 , CO, OCS, N 2 0, NO, OH, o 2 , SO. Also discussed are criteria for the selection of appropriate transitions for the development of high sensitivity monitors to be used in air pollution and combustion research.

Lineshape Measurements of Rotational Line in Millimeter-Wave Region by Second Harmonic Detection

“…The present value of the broadening coefficient of the J = 6 F-5 transition of OCS molecule is an intermediate of the values quoted from the literature: 7.9 MΗz/Tr [11], 6.52 MHz/Tr [12] and 6.4 MHz/Tr [13]. The mean of the three agrees with our result within the experimental error.…”

X band model of Venus atmosphere permittivity

“…The method to estimate the OCS effect on the dielectric constant is similar as the one applied for SO 2 . The Lorentzian function is utilized as the line‐shape function and the line width factor of OCS used is 6.4 MHz/torr as determined by Kolbe et al [1977]. With the Poynter and Pickett [1985] catalog, the simulation shows a negligible dispersion effect of OCS within X band.…”

Observations of the J = 1−0 CO lines in the Mars atmosphere: Radiodetection of 13CO and monitoring of 12CO

“…At the low pressures of Mars atmosphere, the Lorentz and Doppler broadening are comparable, and for modeling the lineshape we used a Voigt profile. The absolute line strengths were calculated assuming a dipole moment of 0.112 D for ~zco (Kolbe et al 1977) and 0.110 D for 13CO (Meerts et al 1977). The collisional broadening constant (CO by CO2) was taken to be 0.11 cm-l/atm at 300°K, with a T -°'75 dependence (Varanasi 1975).…”