15min:

JINJUN LIU, LILY ZU, WEIDONG ZHOU, VLADIMIR LOZOVSKY, PATRICK DUPRÉ, C. BRADLEY MOORE AND TERRY A. MILLER, Laser Spectroscopy Facility, Department of Chemistry, The Ohio State University, Columbus, OH 43210.

The fluorescence-dip infrared (FDIR) spectrum of methoxy radical (CH₃O) has been recorded in the region 2875-2980 cm^-1. Methoxy radical was produced by the photolysis of methyl nitrite (CH₃ONO) in a pulsed free-jet expansion. The laser induced fluorescence (LIF) spectrum obtained was characterized by a rotational temperature of 2K. In the FDIR experiment, the UV excitation laser was tuned to the rotational transition, N'=1, K'=0 J''=3/2, P''=3/2 of the A ²A₁ X ²E_3/2, 0-0 band. Two IR sources were used to deplete the ground-state level: difference frequency mixing and an optical parameter oscillator (OPO). The FDIR spectrum is detected as dips in fluorescence as a function of IR frequency. The correlation between the FDIR spectrum, the IR absorption spectrum, the stimulated emission pumping (SEP) spectrum and the dispersed fluorescence (DF) spectrum will be discussed.