Multiple Scattering Debye-Waller Factors for Arsenate

Debye-Waller factors for the As-O-O triangular multiple scattering paths within the arsenate in Na2HAsO4 center dot 7H(2)O are evaluated in terms of magnitude ratio with respect to the Debye-Waller factor of the nearest neighbour As-O shell (sigma(2)(AS-0-0)/sigma(2)(AS-0)). The arsenates are studied under two different levels of distortion from an ideal tetrahedron, i.e. a relatively high distortion in the powder form and a nearly ideal tetrahedron in an aqueous solution at pH 14. The Debye-Waller factor ratio sigma(2)(AS-0-0)/sigma(2)(AS-0) is found to be 2.0 and 1.9 for the powder and liquid sample, respectively, appearing to be insensitive to the distortion of the arsenate tetrahedron.