OBSERVATION OF DYNAMIC STARK SPLITTING IN INFRARED-INFRARED DOUBLE RESONANCE IN METHYL FLUORIDE

$^{1}$G. Magerl, W. Schupita, and E. Bonck, IEEE J. Quantum Electron. QE-18, 1214-1220 (1982).""Author Institution: Department of Chemistry, Michigan State UniversityDynamic Stark splitting (Rabi splitting) has been observed in the P(5,3) transition in the $2\nu_{3}\leftarrow \nu_{3} $ band of $^{12}{{CH}_{3}F}$ while pumping the R(4,3) transition in the $\nu_{3}$ band with 1-5 W of infrared power from a 9P(32) $^{12}{C^{18}O_{2}}$ laser. The splitting was observed by scanning the probe transition by means of an infrared microwave sideband laser of the Magerl design${.}^{1}$ The lineshape of the double resonance effect has been fit to good accuracy by means of a least -squares fitting program that solves the density matrix equations for a three-level system followed by integration over the molecular velocity and summation over the spatially-degenerate m states. The effects on the lineshape of changes in pressure and pumping power, of non-parallel pump and probe beams, and of frequency jitter in either of the lasers will be described. A corresponding splitting has also been observed in the Q(12,9) and R(12,9) transitions in the $2\nu_{3}\leftarrow \nu_{3} $ band of $^{13}{CH_{3}F}$ while pumping the R(11,9) transition in the $\nu_{3}$ band with the 9P(22) $^{12}{C^{18}O_{2}}$ laser. No splitting was observed in the R(12,2) transition in the hot band of this molecule while pumping the Q(12,2) transition in the fundamental band with the 9P(20) $^{12}C^{16}O_{2}$ laser. The theoretical reason for the lack of splitting in this double-resonance combination will be discussed. The R(4,3) transition in the $\nu_{3}$ band of $^{13}CH_{3}F$ has been simultaneously pumped and probed in a two-level double-resonance experiment and the resulting spectrum has been used to obtain a precise value for the offset of the frequency of this transition from the 9P(32) $^{12}C^{18}O_{2}$ laser