Knowledge Bank

A Fourier-transform infrared spectrum of 91% $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}CD4$ has been recorded between 885 and $1193cm-1$ with a resolution of $0.04cm-1$. The frequencies of 600 lines were measured with an accuracy of $0.003cm-1$. Of these, approximately 368 are assigned to allowed transitions in $\nu 4,95$ to forbidden $\nu 4$ transitions, and 137 to $\nu 2$; maximum upper-state J values are 20 for $\nu 4$ and 19 for $\nu 2$. An interacting-band analysis of the $\nu 2/\nu 4$ diad yields spectroscopic constants for these Coriolis-coupled fundamentals and fits the experimental frequencies with a standard deviation of $0.0038cm-1$. A $\nu 4p+(12)$ transition at $943.3812cm-1$, nearly coincident with the 10P(22) emission line of the $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}C16O2$ laser, has been investigated by heterodyne spectroscopy and its detuning (-64 MHz) and absorption coefficient determined. Such coincidences may lead to the development of laser analytical techniques for $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}CD4$, which is a useful non-radioactive atmospheric tracer. $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}CD4$ transitions that are close to isotopic $CO2$ laser lines have been determined for this purpose and for use in double-resonance experiments.