Temporary negative ion resonances in benzene and benzene derivatives

New, intense, energy loss resonances below the first excitation potential were discovered in the electron impact excitation spectra of benzene and six of its derivatives. The observed resonances for o-C₆H₄CH₃Cl, C₆H₅Cl, C₆H₅Br and o-₆H₄Cl₂ peak at exactly the same energy as the dissociative electron capture resonances previously reported for these compounds, suggesting that both resonances proceed via a common temporary negative ion state of the parent molecules.