Calculation of the Absorption Cross Sections of Some Molecules from GEISA Database at the Wavelengths of Isotopically Different CO2 Lasers

Asylkhan Rakhymzhan,Alexey Chichinin

doi:10.1155/2013/592971

Abstract

A calculation of the absorption cross section of some molecules (NH3, C2H4, CO2, O3, NO2, PH3, HNO3, SF6, CH3OH, HCOOH, OCS, CH3CN, C2H6, SO2, and H2O) at the wavelengths transmitted by a CO2 laser filled with different isotopes (12C16O2, 13C16O2, 12C18O2, 14C16O2, 14C18O2, 13C18O2, and 12C16O18O) 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 CH3OH and HCOOH at low pressures for all these CO2 lasers are also presented. These calculations are provided for design of new CO2-laser-pumped far-infrared lasers.

Highlights

In this paper we report molecular absorption cross sections σ(M) at CO2-laser emission frequencies for several selected gases of atmospheric relevance (M = NH3, C2H4, CO2, O3, NO2, PH3, HNO3, SF6, CH3OH, HCOOH, OCS, CH3CN, C2H6, SO2, and H2O)
Note that the LIDAR technique sometimes is used for remote sensing of some exotic gases, like, for example, chemical warfare [13]
In some cases (CH3OH and HCOOH) it may be used in designing optically pumped FIR lasers where CO2 laser is used as a source of a pump radiation [14]

Summary

Introduction

In this paper we report molecular absorption cross sections σ(M) at CO2-laser emission frequencies for several selected gases of atmospheric relevance (M = NH3, C2H4, CO2, O3, NO2, PH3, HNO3, SF6, CH3OH, HCOOH, OCS, CH3CN, C2H6, SO2, and H2O) This information may be useful mainly in the differential absorption (Light Detection and Ranging) LIDAR technique for remote measurement of the gas species [1,2,3,4,5,6,7,8] and may be used to monitor the CO2 content in fuel combustion products [9], remote sensing of gases in human breath [10], or multiphoton dissociation processes or to measure water vapor concentration and wind speed vector in the plume of volcano [11, 12]. The focus of the present study is to predict absorption cross section in pure air at wavelengths of seven isotopic

Results

Discussion

Conclusion