XPS study of mica surfaces

Muscovite mica surfaces were studied with X-ray photoelectron spectroscopy. The air-cleaved mica surfaces showed a large C1s peak in the range 285.3–285.9 eV indicating the presence of carbon species other than the adventitious. Normal emission and grazing emission spectra were utilised to calculate bulk and surface elemental ratios respectively for air-cleaved as well as vacuum-cleaved mica surfaces. Preferential attenuation of some peaks has been proposed for a few abnormal elemental ratios. Apparent shifts in binding energy due to sample charging were investigated for differently treated mica surfaces. Changes in the apparent shift are shown to be due to the existence of strong dipole fields at the surface resulting in a potential drop of as much as 3.6 V across the dipole layer.