Line Broadening and the Temperature Exponent of the Fundamental Band in CO–N2 Mixtures

Abstract We have measured the width, Γ, of many P and R lines of the fundamental vibration–rotation band of CO perturbed by N 2 at 348 K and pressures of about 50 kPa. We have also extended the measurements made earlier at room temperature. The broadening coefficients, γ = Γ/pressure, were obtained with an accuracy of 0.3% by fitting with a Lorentzian, a Voigt, and an empirical lineshape model that blends together a hard-collision model and a speed-dependent Lorentzian profile. In all cases the results are represented by an empirical exponential power law polynomial in the line number, m . Combining the data at the two temperatures yields the exponent n in the scaling law γ( T 1 )/γ( T 2 ) = ( T 1 / T 2 ) − n , as a function of line number. The broadening coefficients and the variation of the temperature exponent line number are compared with theory. In addition, the line-mixing parameters are also reported at 348 and 301 K.