Photoionization of two substituted methyl radicals: Cyanomethyl and bromomethyl

The photoionization of two substituted methyl radicals is presented. Cyanomethyl (CH2CN) and bromomethyl (CH2Br) were generated by flash pyrolysis from chloroacetonitrile and bromonitromethane. Mass-selective threshold photoelectron spectra of both radicals were recorded. The adiabatic ionization energies of CH2CN and CH2Br have been determined to be 10.28 eV ± 20 meV and 8.62 eV ± 10 meV. CH2Br shows a vibrational progression upon ionization that is assigned to the C–Br stretch mode. The photoionization of the precursors as well as the dissociative photoionization of CH2Br were examined. A 0 K heat of formation of 174.5 kJ mol−1 is derived for CH2Br and a C–Br bond dissociation energy of 334.1 kJ mol−1.