Knowledge Bank

Diode laser spectra of individual transitions over a wide range of J in $\nu 4$ of $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}CH4$ have been recorded to determine line strengths for comparison with recent theoretical $tabulations.1,2$ Eleven lines in the range $1202-1317cm-1$, including RO, R1, and P-branch transitions with J = 7 to 15, were each scanned several times at a variety of sample pressures with high photometric precision. The derived strengths agree remarkable well with those for transitions which have been measured $previously.3,4$ The correspondence with calculated $strengths1,2,3$ is generally good, although the measured values at J$ > 10$ are significantly lower than predicted. Techniques for measuring line strengths with a diode laser spectrometer will be discussed.