X-ray Photoelectron spectroscopic and Raman spectroscopic study of bayldonite from Wheal Carpenter, Cornwall, UK

摘要

Bayldonite [CuPb(AsO)(OH)], Wheal Carpenter (Cornwall, UK) was studied by X-ray Photoelectron Spectroscopy and Raman Microscopy. X-ray Photoelectron Spectroscopy revealed single copper, lead and arsenic positions in the crystal structure. Two oxygen bands with a 1:4 ratio were associated oxygen positions in arsenate- and hydroxyl-groups, excluding the presence of acidic arsenate groups. The relatively large difference in binding energy for the two oxygen bands was interpreted as being due to the dynamic Jahn-Teller distortion of the copper octahedral in the bayldonite crystal structure. Raman microscopy showed bands at 804 and 837 cm assigned to arsenate antisymmetric stretching mode and the symmetric stretching mode. Supported by the X-ray Photoelectron Spectroscopic results the bands at 726, 761, 822 and 886 cm were assigned to copper-hydroxyl modes. Bands around 497 cm were assigned to the arsenate antisymmetric bending modes and around 427 cm to the symmetric bending modes. The 539 cm band was associated with a copper-hydroxyl stretching mode or another υ. The region 250–400 cm showed sharp bands at 313 and 328 cm with weaker bands at 298 and 342 cm assigned to copper-oxygen and/or lead-oxygen stretching modes.