On parameterization of spectral line profiles including the speed-dependence in the case of gas mixtures

- An algebraic expression for a model line profile was developed.
- All main physical factors were taken into account.
- The profile's parameters were introduced in the case of gas mixtures.
- The nonlinear dependencies of the parameters on pressure were analyzed.

The physically grounded parameterization of a line profile including the speed-dependence was performed. It was shown that two actual parameters of the quadratic speed-dependence appear in gas mixtures instead of a single parameter in a pure gas. One of the parameters is associated with hard elastic velocity-changing collisions; the second is connected with the other sorts of collisions. For comparable concentrations of gas species, they may differ by 50% and depend nonlinearly on partial gas pressures. The dimensionless line narrowing parameter also reveals nonlinear pressure-dependence. The computational expressions for the line profile including all main physical mechanisms of its forming in conditions of gas mixtures are derived.