Stimulated Raman and electronic excitation of CH4–OH reactant complexes

Binary complexes composed of OH and CH4 reactants have been stabilized in a shallow well in the entrance channel to the hydrogen abstraction reaction. The CH4–OH reactant complexes are identified by laser-induced fluorescence in the OH A 2Σ+–X 2Π (1,0) and (0,0) spectral regions as well as by stimulated Raman excitation in the vicinity of the symmetric stretching mode (ν1) of CH4. The binding energy of CH4–OH is found to be 210±20 cm−1 in its ground electronic state and increases slightly upon vibrational excitation of the ν1 mode of methane.