[Analysis of gas absorption coefficient at various pressures].

The absorption coefficient alpha(v) of gas plays an important role in quantitative analysis of pollution gases and theoretical investigation of molecular parameter. In this paper we first analyze alpha(v) theoretically and present a calculation method. Then we analyze 2v3 band R3 manifold of pure CH4 and draw a conclusion that alpha(v0) decreases and the peak absorption kappa(v0) increases with increasing the pressure. When the pressure is <0.03 and >2 atm, we can calculate alpha(v0) using the Gaussian profile and Lorentzian profile respectively, and then analyze the relative error. Finally we analyze the peak absorption kappa(v0) at various pressures, then define the high-resolution area and high-sensitive area respectively when the pressure is <0.01 and >1 atm.