Knowledge Bank

We have measured the broadening of several rotovibrational transitions of the $\nu 2$ band of $NH3$ caused by collisions with foreign gases as $He,H2$ and $N2$. As expected the values of pressure broadening are smaller than those measured previously in the case of self broadening $\mathrm{<mrow\; data-mjx-texclass="ORD">(1)</mrow>}$. However, a smaller broadening infers a smaller impact parameter so that the Anderson’s approximation in the frame of the impact theory begings to fail. Nevertheless, we are trying to apply this theory in the case of $N2$-broadening, because of the slight bigger values of the impact parameter with respect to the other gases. The results of such calculation will be presented along with a critical analysis of the experimental data. (1) G. Baldacchini, G. Buffa, S. Marehetti, V. Montelatiei and O. Tarrini: J. Chem. Phys. 76, 5271 (1982); same authors with V. Sorge; J. Chem. Phys. (1983)