PUB - Publikationen an der Universität Bielefeld

The 000 band of the CH3 3pz 2A"2 X~ 2A"2 Rydberg transition has been recorded using the (2 + 1) resonance-enhanced multi-photon ionization (REMPI) of CH3 at 333 nm. 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 3pz 2A"2 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 CH 3 concentrations from measured REMPI peak intensities of the dominant Q branch.