Influence of the tip of the scanning tunneling microscope on surface electron lifetimes

The results of many-body GW calculations are reported which quantify the influence of the electric field that exists between the surface and the tip of a scanning tunneling microscope (STM) on the inelastic lifetimes of image state electrons. The tip-induced field causes a significant increase in inelastic scattering, reducing the lifetimes of n = 1 image state electrons at Cu(0 0 1) and Ag(0 0 1) by over 50% under typical tunneling conditions used in the STM, and even more for higher members of the image state series. The reduced lifetimes result from changes in the image state wave functions, which exhibit greater penetration of the metal surface, and an increase in the number of inelastic scattering channels that are available for decay.