The ionization energy of methylene (CH2) from a rotationally resolved photoelectron spectrum and its thermochemical implications

The adiabatic ionization potential of methylene has been determined to be 83772+/-3 cm(-1) from a rotationally resolved photoelectron spectroscopic study of the CH2+ (X) over tilde (2)A(1) (0,0,0)<--CH2 (X) over tilde B-3(1)(0,0,0) transition. This value was used to determine thermochemical quantities such as the 0 K dissociation energy of the ketene cation in CO and CH2+ D-0(CH2=CO+)=33202+/-7 cm(-1), the 0 K dissociation energy of the methyl radical D-0(CH2-H)=38179+/-49 cm(-1), the 0 K dissociation threshold of methane in CH2 and H-2 D-0(CH2-H-2)=38232+/-50 cm(-1) and the 0 K enthalpy of formation of CH2 Delta(f)H(-)(CH2,T=0 K)=390.73+/-0.66 kJ mol(-1). (C) 2002 American Institute of Physics.