An (e,2e) coincidence study of formic acid monomer and dimer

We report asymmetric coplanar (e,2e) spectroscopy binding energy spectra for formic acid monomer and dimer. We believe the dimer investigation represents the first time (e,2e) has been used to study a system involving intermolecular forces. The experimental work is supplemented by density functional theory and outer valence Green's function calculations to assist the interpretation of the electronic structures. The plane wave impulse approximation in combination with wavefunctions calculated using the B3LYP/TZVP level of theory appear to be appropriate for the monomer, however, this combination fails for the dimer.