Determination of the linewidth dependence on foreign-gas pressure for 3.4-μm DF spectra

Measurement of $v=1-0\mathrm{}$, $P$-branch 3.4-μm DF absorption spectra is made for DF mixed with foreign gases at a temperature of 23-25°C. A cw DF laser is used as a light source, and laser intensity transmitted by the gas mixture is measured in order to determine the absorption. From the measured absorption, the ratio of cross sections $\frac{Q_{\mathrm{AB}}}{Q_{\mathrm{AA}}}$ is determined, where $Q_{\mathrm{AB}}$ is the cross section for collision of DF $\mathrm{}(=A)\mathrm{}$ with a foreign gas $\mathrm{}(=B)\mathrm{}$ and $Q_{\mathrm{AA}}$ is for DF self-collisions. Results are obtained for the single line $v=1-0\mathrm{}$, $P\left(8\right)\mathrm{}$ in the case of ${\mathrm{D}}_2$, He, ${\mathrm{N}}_2$, C${\mathrm{F}}_4$, and S${\mathrm{F}}_6$ and for the lines $v=1-0\mathrm{}$, $P(5-10)\mathrm{}$ in the case of HF.