A theoretical study on the ionic states, with analysis of vibrational levels of the photoelectron spectrum, of formic acid (CH2O2 and CD2O2) Original Research Article

Ab initio calculations are performed to study the molecular equilibrium structures and the vibrational levels of the low-lying 2A′ and 2A″ states of formic acid (CH2O2). The theoretical intensity curves obtained by the Franck-Condon factors for ionization transitions are also reported and compared with the photoelectron spectra of CH2O2 and CD2O2. Some new assignments of the vibrational levels of the photoelectron spectrum are proposed.