Calculation of the Absorption Cross Sections of Some Molecules from GEISA Database at the Wavelengths of Isotopically Different CO 2 Lasers

A calculation of the absorption cross section of some molecules (NH 3 , C 2 H 4 , CO 2 , O 3 , NO 2 , PH 3 , HNO 3 , SF 6 , CH 3 OH, HCOOH, OCS, CH 3 CN, C 2 H 6 , SO 2 , and H 2 O) at the wavelengths transmitted by a CO 2 laser filled with different isotopes ( 12 C 16 O 2 , 13 C 16 O 2 , 12 C 18 O 2 , 14 C 16 O 2 , 14 C 18 O 2 , 13 C 18 O 2 , and 12 C 16 O 18 O) is presented. The spectroscopical parameters for the molecules from GEISA database have been used. Hence the selection of the molecules was substantially based on the availability of the parameters in the database. The results of the calculations may be used in designing the differential absorption technique for remote monitoring of these molecules. The pressure and temperature dependence of the cross sections are described by and coefficients; these coefficients were calculated for the largest absorption cross sections for each molecule. The absorption cross sections of CH 3 OH and HCOOH at low pressures for all these CO 2 lasers are also presented. These calculations are provided for design of new CO 2 -laser-pumped far-infrared lasers.