Pulsed neutron diffraction of phosphorous acid and its aqueous solution with inactivation capability of activated oxygen

Pulsed neutron diffraction was carried out to analyze an intramolecular structure of D₃PO₃ and an orientational characteristic of adjacent molecules in D₃PO₃-nD₂O (n = 0; 1 and 20) solutions by using the high intensity total scattering spectrometer in High Energy Accelerator Research Organization (KEK) at Tsukuba, Japan. The radial distribution method and the correlation method were employed for the analysis of structural parameters such as interatomic distances, coordination numbers and temperature factors, being consulted with those by simulations. The intramolecular structure of the phosphorous acid in the liquid state did not differ much from that in the crystalline state. In the liquid phosphorous acid, two intramolecular P-O bonds were recognized, the shorter P-O bond being assigned to the P-O double bond and the longer P-O to the single bond. On addition of heavy water, the coordination numbers of the intramolecular P-O correlations, i.e. both the shorter P-O double bond and the longer P-O single bond, increased a little.