Role of the electric field in surface electron dynamics above the vacuum level
J. I. Pascual, C. Corriol, G. Ceballos, I. Aldazabal, H.-P. Rust, K. Horn, J. M. Pitarke, P. M. Echenique, A. Arnau
Abstract
Scanning tunneling spectroscopy (STS) is used to study the dynamics of hot electrons trapped on a Cu(100) surface in field emission resonances (FER) above the vacuum level. Differential conductance maps show isotropic electron interference wave patterns around defects whenever their energy lies within a surface projected band gap. Their Fourier analysis reveals a broad wave vector distribution, interpreted as due to the lateral acceleration of hot electrons in the inhomogeneous tip-induced potential. A line-shape analysis of the characteristic constant-current conductance spectra permits to establish the relation between apparent width of peaks and intrinsic line-width of FERs, as well as the identification of the different broadening mechanisms.