STUDIES OF THE CALCITE CLEAVAGE SURFACE FOR COMPARISON WITH CALCULATION

The cleavage face of single-crystal calcite has been studied in vacuum using reflection electron energy-loss spectroscopy (REELS), X-ray photoelectron spectroscopy (XPS), and electron-stimulated desorption (ESD). XPS valence-band measurements and a REELS determination of the band gap were made for comparison with a density-functional-theory calculation of the electronic and structural properties of calcite; both measurements compare well to the theory. A flux of 200 V electrons was found to damage the calcite surface at exposures of approximately 0.01 C/cm2 or greater. This damage narrowed the band gap at the surface and caused the emission Of CO2.