THE CH3 3PZ (2)A2''[-(X)OVER-TILDE (2)A(2)''O(0)0 BAND AT TEMPERATURES UP TO 1700-K INVESTIGATED BY REMPI SPECTROSCOPY

The 0(0)0 band of the CH3 3p(z)2A2'' <-- X2A2'' Rydberg transition has been recorded using the (2+1) resonance-enhanced multiphoton ionization (REMPI) of CH3 at 333 run. CH3 was generated in a discharge flow reactor at room temperature and in a hot-filament-assisted chemical vapor deposition (HFCVD) reactor at temperatures of 820 to 1700 K. By means of spectral simulation the rotational constants, B0' and C0', and the rotational state-dependent predissociation rates of the 3p(z) 2A2'' state were determined. Based on these constants and the well-known rotational and vibrational ground-state constants, relative intensities of the CH3 REMPI spectra were calculated for temperatures up to 2300 K. These spectra were used to evaluate relative CH3 concentrations from measured REMPI peak intensities of the dominant Q branch.