Spectroscopy of ^12CF_4 features near the 9-μm ^12C^16O_2R(10), R(12), and R(18) lines by CO_2-laser and diode-laser spectroscopy

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Abstract
The 12CF4 molecule has been made to lase at various wavelengths in the 16-μm ν4 + ν2 → ν2 band by pumping in the 9-μm 0 → ν2 + ν4 band with 12C16O2 lines. The strongest reported 12CF4 laser line occurs at 615.06 cm−1 and is pumped by 9R12 [9-μm band, R(12) line]. We have measured, by two techniques, the absorption of 12CF4 in 9R12, and also in 9R10 and 9R18, which are known to result in weak 16-μm laser transitions. This was done both at room temperature and at an estimated 100 K, and striking changes in spectral features were noted as the temperature was lowered. For the 9R12 laser line, we find a 12CF4 feature located 30 ± 3 MHz to the high-frequency side of line center, with a peak absorption coefficient of 5 × 10−4 to 9 × 10−4 cm−1 Torr−1, depending on temperature. By contrast, there are only weak 12CF4 features within ±40 MHz of the 9R10 and 9R18 laser-line centers, and the absorption coefficients of those features are 1 × 10−4 to 2 × 10−4 cm−1 Torr−1.