X-ray photoelectron spectroscopy of Single Crystals of intercalated Bismuth Selenide*

The possibility of superconductivity in topological insulators is likely to yield new physics, especially because the insulating normal state is highly unconventional. However, before moving on to microscopic theory, it is important to characterize and study basic systems available today. Here, we present XPS studies of intercalated single crystals of Bi$_{2}$Se$_{3}$ and Sb$_{2}$Se$_{3}$. Core level spectroscopy, combined with infra-red and Raman spectroscopy, yield details of the nature of bonding of atoms at the cleaved surface.