Heat of formation for the formyl cation by photoionization mass spectrometry

Abstract

The ionization energies and HCO + appearance energies for a series of organic compounds have been measured by dissociative photoionization mass spectrometry. A 298 K heat of formation of 825.6±2.7 kJ mol −1, based on the stationary electron convention, is derived for the formyl cation in the gas phase which results in an absolute proton affinity for CO of 594±3 kJ mol −1. From a discussion of the heat of formation for the formyl radical, the adiabatic ionization energy for HCO is estimated to be 8.10±0.05 eV.