Broadening and Collisional Interference of Lines in the IR Spectra of Ammonia: Self-Broadening in the ν1 Band

The relaxation parameters of the lines of the P, Q, and R branches of the nu(1) ammonia nu(1) band are calculated in the case of self-broadening. In the case of doublets, the effects of collisional interference of the doublet components have been taken into account. It is shown that the cross-relaxation parameters of the components can reach similar to 60% of the values of the self-broadening coefficients, which gives rise to the narrowing of the components and indicates that the isolated line approximation is inapplicable. Comparison with experimental data is made. Good agreement for self-broadening coefficients is obtained. In the case of the self-shift coefficients, discrepancies are considerable in both magnitude and sign, and it is impossible to elucidate their reasons without invoking additional experimental data.