Knowledge Bank

The fluorescence-dip infrared (FDIR) spectrum of methoxy radical (CH$3$O) has been recorded in the region 2875-2980 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$. Methoxy radical was produced by the photolysis of methyl nitrite (CH$3$ONO) in a pulsed free-jet expansion. The laser induced fluorescence (LIF) spectrum obtained was characterized by a rotational temperature of ${\sim}$2K.IntheFDIRexperiment,theUVexcitationlaserwastunedtotherotationaltransition,N$^{\prime}$=1,K$^{\prime}$=0 $\leftarrow$ J=3/2, P=3/2 of the $A~$ $2$A$1$ $\leftarrow$ $X~$ $2$E$\mathrm{<mrow\; data-mjx-texclass="ORD">3<mrow\; data-mjx-texclass="ORD">/</mrow>2</mrow>}$, 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,} \underline{\textbf{117}}, 6538, (2002)} the stimulated emission pumping (SEP) spectrum and the dispersed fluorescence (DF) spectrum will be discussed.