The inelastic neutron scattering spectrum of chromous acid at high energy transfers

The inelastic incoherent neutron scattering spectrum of chromous acid, at 77 K, is presented. It is dominated by the intense bending mode at 1254 cm−1 with some modes at lower frequencies showing indications of dispersion. The antisymmetric stretch νas(OHS) {‖1〉‐‖2〉} was assigned to a broad band centered at ∼2050 cm−1, significantly displaced for the IR assignment (1650 cm−1). The breadth of the band is due to the dispersion, and kinematic coupling, that is anticipated for this compound. These new data allows us to fit chromous acid more clearly into the general trend of hydrogen bonded compounds. Chromous acid compares very well in its overall INS spectrum with the isomorphous sodium bifluoride, except that the kinematic coupling between νas(OHO) and the symmetric stretch does not occur in this compound.

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