Vibration Spectra of Hydrogen Bonds by Neutron Energy-Loss Spectrometry

A neutron spectrometer with a beryllium-filter detector has been used to obtain vibration spectra of a selection of hydrogen-bonded compounds in the range 400–1400 cm−1. The neutron technique preferentially observes hydrogen motions, thus providing a less ambiguous assignment of modes than is possible in optical spectroscopy. Data are reported here for KHF2, CsHCl2, CsDCl2, NaHCO3, KH(CF3COO)2, and KH(CCl3COO)2. In the first three compounds the results provide confirmation of existing infrared and Raman assignments, and in the latter three cases the locations of the bending modes are indicated.