M. ISHIGURO, T. IMAJO, K. HARADA, K. TANAKA AND T. TANAKA, Department of Chemistry, Faculty of Science, Kyushu University 33, Hakozaki, Higashi-ku, Fukuoka 812-81, Japan.
A discharge modulation technique has been applied to color center laser spectroscopy for the detection of radical species generated in a pulsed supersonic jet . Transitions in the 3 band of the CH3 radical rotationally cooled to 23 K were recorded by the phase sensitive detection technique with an improved signal to noise ratio. The sensitivity attained corresponds to 6× 10-5 absorption.