A study of the singlet and triplet states of vinylidene by photoelectron spectroscopy of H2C=C−, D2C=C−, and HDC=C−. Vinylidene–acetylene isomerization

摘要: The X 1A1, a 3B2, and b 3A2 states of vinylidene are observed in the ultraviolet (351.1–364.0 nm) photoelectron spectra X 2B2 H2CC−, D2CC−, X 2A’ HDCC−. X 1A1 state exhibits vibrational structure well above barrier for isomerization to acetylene. A strict lower bound lifetime singlet against rearrangement is τ>0.027 ps, with an estimate τ≊0.04–0.2 ps based on a simulation line shapes including rotational broadening. analysis triplet bands provides frequencies estimates changes molecular geometries between anion neutral species. qualitative potential energy surface CH2 rock mode, which closely corresponds reaction coordinate isomerization, extracted from experimental data. adiabatic electron affinity EA(X 1A1 H2CC)=0.490±0.006 eV term energies T0(a 3B2 H2CC)=2.065±0.006 T0(b 3A2 H2CC)=2.754±0.020 eV. Exp...