Knowledge Bank

Air-broadened and $N2$-broadened halfwidths at room temperature for 25 lines in the $\nu 4$ band of $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}CH4$ have been determined from infrared absorption spectra recorded with a tunable diode laser (TDL) system in selected spectral regions between 1250 and $1360cm-1$. Air-broadened halfwidths for 20 of these lines were also determined from additional spectra at $0.01cm-1$ resolution recorded with the Fourier transform spectrometer (FTS) system in the McMath solar telescope complex on Kitt Peak. The air-broadened halfwidth values obtained from these two techniques are very consistent with agreement to better than 3% for most lines. Several additional lines of $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}CH4$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}CH3D$ were also measured in the same spectral region with the diode laser system. The measured $N2$-broadened and air-broadened halfwidths will be reported.