Knowledge Bank

The ratio of the foreign gas broadening efficiency to the self broadening efficiency can be determined for the lines of the HF fundamental vibration band with a prism spectrometer. These ratios, together with self broadened line widths determined by Kuipers, can be used to evaluate line width parameters for foreign gas broadeners. These line breadths show different J variations for different foreign gases. A rather detailed agreement between collision diameters derived from the R(O) line breadth and the collision diameter for the $NH33-3$ microwave $line1$ is found. The University of Tennessee grating spectrometer has been used to examine some of the R branch lines of the HF vibration spectrum in samples containing 0.1 to 0.2 mole per cent HF at 5 atmospheres pressure. In eighteen experiments involving some combination of the five lines and six foreign gases, line center shifts were observed in twelve instances. Shifts as large as $0.65cm-1$ were observed for the R(O) line broadened with $SO2$. When shifts were observable, the R(O) line was always shifted to higher wave numbers, and the other lines to lower wave numbers. With the more efficient broadeners the line was broad compared with the spectrometer transmission function, and the shape of the line was directly determined with fair accuracy. When broadened with HC1 the line is nicely fit by a Lorentz line shape. When broadened with $SO2$ there is not only a shift, but also a pronounced asymmetry about the line peak with the high frequency side of the line being the stronger.