Sub-Doppler spectroscopy by use of microwave sidebands of CO₂ laser lines applied to the C-O stretching fundamental band of methanol

Microwave sidebands of CO₂ laser lines were used as an infrared source in infrared microwave double resonance spectroscopy and infrared saturation spectroscopy to study the C-O stretching fundamental band of methanol. In the former application, rotational lines in the v_CO = 1 state have been observed with good signal to noise ratios and physical processes involved in this method have been discussed. In the latter method, (vt, A/E, K) = (2, A, 4) sequence transitions in the C-O stretching fundamental band have been identified and term values for the (2, A, 4) levels in the v_CO = 1 state have been determined.