Raman microscopy of synthetic goudeyite (YCu6(AsO4)2(OH)6·3H2O)

Raman microscopy has been used to study the molecular structure of a synthetic goudeyite (YCu6(AsO4)3(OH)6·3H2O). These types of minerals have a porous framework similar to that of zeolites with a structure based upon (A3+)1−x(A2+)xCu6(OH)6(AsO4)3−x(AsO3OH)x. Two sets of AsO stretching vibrations were found and assigned to the vibrational modes of AsO4 and HAsO4 units. Two Raman bands are observed in the region 885–915 and 867–870 cm−1 region and are assigned to the AsO stretching vibrations of (HAsO4)2− and (H2AsO4)− units. The position of the bands indicates a C2v symmetry of the (H2AsO4)− anion. Two bands are found at around 800 and 835 cm−1 and are assigned to the stretching vibrations of uncomplexed (AsO4)3− units. Bands are observed at around 435, 403 and 395 cm−1 and are assigned to the ν2 bending modes of the HAsO4 (434 and 400 cm−1) and the AsO4 groups (324 cm−1).