Damping Effects in Angular-Resolved Ultraviolet Photoemission Spectroscopy on Cu(111)

Decay of electronic excitations at metal surfaces

“…After ion bombardment the width increased to 400 meV. This increase in width, connected with increasing asymmetry into the direction of the k k -dispersion of the state, was interpreted as a disorder-induced relaxation of the sharpness of k k [107].…”

“…It has been realized already early in the history of photoemission that both the screened and decaying hole left behind with a certain lifetime t h and the finite escape depth of the photoelectron (resulting in an uncertainty of the electron wave vector k ? perpendicular to the surface) contribute significantly to the experimentally observed lineshape [105][106][107][108]. In fact, bulk direct-transition linewidths are in most cases dominated by the final-state damping, see e.g.…”

“…In particular the state around G on Cu(1 1 1) has attracted considerable interest. Slagsvold et al [107] stated in 1983 that ''the problems of sample preparation, instrumental resolution and interpretation of spectra turn the reliable measurement of lifetimes into a demanding endeavor''. With the resolution parameters then available, they resolved the peak at Gðk k ¼ 0Þ with an FWHM of 250 meV on the annealed Cu(1 1 1) sample.…”

Modelling of Angle Resolved Photoemission Spectra at Low Energy

“…For Cu we take IIm ,Zel = 0.4 eV which is greater than estimated in [4]. Next, let US consider the initial state band.…”

“…Thus, unlike three-step model calculations, which cannot describe surface state effects, a direct comparison is possible of surface and bulk peak characteristics of the spectra. A topic of current interest is the determination of electron and hole lifetimes from measurements of values of the full width a t half maximum (FWHM) of t,he energy distribution (see [4] and [5] and references therein). The interpretation is commonly based on a Lorentzian broadening of the spectral function.…”