Knowledge Bank

$N2$-broadened halfwidths have been measured for 51 lines belonging to the $\nu 3$ fundamental band of hydrogen cyanide ($\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}H12C14N$). Data were obtained at room temperature ($\simeq$299K) using a Fourier transform interferometer spectrometer with a nominal resolution of $0.06cm-1$. Spectra were recorded in the region from 3200 to $3400cm-1$, using a 10-cm absorption cell with broadening gas pressures varying from 150 to 700 torr. The halfwidth values were obtained through a nonlinear least squares spectral fitting procedure, and are generally consistent from scan to scan. The resulting $N2$-broadened halfwidths, determined for all lines with $j\le 25$ in both the P and R branches, are smaller than $CO2$-broadened halfwidths, but larger than Ar-broadened halfwidths measured for the same $band1$, and also show a decrease in halfwidth for increasing J. HF-broadened HCN halfwidths have also been measured in spectra of 3 separate 10-cm absorption cells, each filled to a total pressure of approximately 150 torr with a 50-50 mixture of HF and $N2$ and containing several hundred ppm of HCN. An oscillatory dependence of the halfwidth on m, indicative of near-resonant dipole-dipole interactions between HF and HCN, has been observed and is consistent with a similar m-dependence previously measured for HCN broadened by HC$\ell .1$ $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$R. J. Thibault, A. G. Maki and E. K. Plyler. J. Opt. Soc. Am. 53, 1255 (1963).