title: Quantitative X-ray Absorption and Emission Spectroscopies: Electronic Structure Elucidation of Cu2S and CuS.
abstract: The electronic structures of Cu2S and CuS have been under intense scrutiny, with the aim of understanding the relationship between their electronic structures and commercially important physical properties. Here, X-ray absorption and emission spectroscopic data have been analyzed using a quantitative, molecular orbital (MO) based approach to understand the electronic structure of these two complex systems. Cu2S is shown to have a significant amount of Cu2+sites and therefore Cu0centers. The presence of low-valent Cu is correlated with the electrical conductivity of Cu2S, especially at high temperatures. CuS is shown to have tetrahedral Cu2+and trigonal Cu1+sites, with crystal planes that have alternating high and low charge on the Cu centers. These alternating charges may contribute to internal energy transitions required for photoluminescence properties. The in-depth electronic structure solutions presented here not only solve a complicated much-debated problem, but also demonstrate the strength of quantitative MO based approach to X-ray spectroscopies.
authors.affiliation: Materials Chemistry Group, Department of Chemistry, University of Delhi, Delhi, India, 110007 ; Tel: +91-27662650.
authors.forename: Prashant
authors.initials: P
authors.lastname: Kumar
authors.forename: Rajamani
authors.initials: R
authors.lastname: Nagarajan
authors.forename: Ritimukta
authors.initials: R
authors.lastname: Sarangi