Surface sensitivity of esca for sub-monolayer quantities of mercury adsorbed on a gold substrate

A study of the in tensity changes in the X-ray photoelectron 4f_7/2 lines during the formation of multilayers of Hg on Au at low temperature (< 100° K) gives an escape depth, λ_e, of ca. 9A for ≈ 1400 eV electrons, 0.2% of a monolayer of mercury can be detected.