Hydrogen bonding and hydrogen motion in some alkali metal dicarboxylates studied using incoherent inelastic neutron scattering spectroscopy

Abstract

Incoherent inelastic neutron scattering spectra of MH(CO 2CX 3) 2, M  Na, K; X  F, Cl are presented for energy transfers in the range 350 → 2000 cm −1. Despite the complexity of these salts the observation of those normal modes of vibration which involve motion of the hydrogen atom is relatively simple. This is primarily due to the sensitivity of incoherent neutron scattering spectroscopy to the motion of hydrogen atoms and to the availability of an intense source of high energy neutrons. In the case of KH(CO 2CF 3) 2 we were able to determine which of the two previously published assignment schemes, based on optical data, for the vibrations of the hydrogen bond is the correct one. Several different methods of predicting the intensities of neutron scattering bands were tried and the results compared with the observed values.