  High level ab initio calculations were undertaken on the CH$_2$OO anion and
neutral species to predict the electron affinity and anion photoelectron
spectrum. The electron affinity of CH$_2$OO, 0.567 eV, and barrier height for
dissociation of CH$_2$OO$^-$ to O$^-$ and CH$_2$O, 16.5 kJ mol$^{-1}$, are
obtained by means of the W3-F12 thermochemical protocol. Two major geometric
differences between the anion and neutral, being the dihedral angle of the
terminal hydrogen atoms with respect to C-O-O plane, and the O-O bond length,
are reflected in the predicted spectrum as pronounced vibrational progressions.
