Knowledge Bank

Approximately 350 transitions in the $\nu 3$ band and 80 transitions in the $2\nu 3\leftarrow \nu 2$ band of $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}CH,F$ have been recorded by means of an infrared-microwave sideband laser $spectrometer.2$ The infrared source for the CdTe sideband generator is a Lamb-dip stabilized $CO2$ laser. The microwave source is a computer-controlled frequency-stabilized backward wave oscillator operating in the 8-18 GHz region and amplified by a traveling wave tube amplifier. The effect of radiation at the infrared carrier frequency was suppressed by using a polarizer and by chopping the microwave field at 33 kHz. Only the 33 kHz component of the output of the infrared detector was recorded. The sideband generator was operated in the traveling wave mode and the Doppler-limited spectra were recorded in a single pass of a 1-meter cell at pressures ranging from 100 m Torr for the fundamental transitions to 2 Torr for the hot band. The recorded lineshapes were fit to a Gaussian function and the accuracy of the center frequencies is estimated to be better than $\pm 0.00003cm-1$ in favorable cases. Nearly all of the transitions have been assigned and the frequencies of non-overlapping lines have been fit to power series in J(J+1) and $K2$. Transitions included in the fitting involve J and K values up to J=47 and K=18 for the fundamental and J=25 and K=10 for the not band. The resulting vibration-rotation parameters will be reported.