Sub-Doppler spectroscopy of mixed state levels in CH2.

Perturbations in the 716 and 818 mixed singlet/triplet levels of ã 1A1(0,0,0) methylene, CH2, have been reinvestigated by frequency-modulated laser sub-Doppler saturation spectroscopy. The hyperfine structure was completely resolved for both the predominantly singlet and the predominantly triplet components of these mixed rotational levels using b 1B1-ã 1A1 optical transitions near 12 200 cm-1 with megahertz resolution. The mixing coefficients were obtained from the observed hyperfine splittings and a two-level deperturbation model. The analysis also determines the energy separation of the unperturbed zero-order levels and the unperturbed hyperfine splittings for the triplet perturbing levels 615 X 3B1(0,3,0) and 937 X 3B1(0,2,0). [ABSTRACT FROM AUTHOR]