Direct evidence for the nature of core-level photoemission satellites using angle-resolved photoemission extended fine structure

Abstract

Photoemission satellites from several systems have been found to exhibit exactly the same angle-resolved photoemission extended fine structure (ARPEFS) as found in the main peaks, when referred to the equivalent photoelectron wave number $k$ for their own photoelectrons. This provides a direct and powerful method for experimentally determining the angular momentum parameters and the intrinsic/extrinsic nature of core-level photoemission satellites. We present ARPEFS satellite data for nitrogen $1s$ line in $c(2\ifmmode\times\else\texttimes\fi{}2){\mathrm{N}}_{2}/\mathrm{Ni}(100)$, the nickel $3p$ line in clean nickel (111), the carbon $1s$ lines in $(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3})R30$ CO/Cu(111) and $p2mg(2\ifmmode\times\else\texttimes\fi{}1)\mathrm{CO}/\mathrm{Ni}(110)$, and the cobalt $1s$ line in $p(1\ifmmode\times\else\texttimes\fi{}1)$ Co/Cu(100). For the last two cases the ``satellite'' structure is actually the low-energy tail of a Doniach-Sunjic line shape. The satellite peaks and the tails of the Doniach-Sunjic line shapes exhibit ARPEFS curves that in all cases except one indicate angular-momentum parameters identical to the main peak and an intrinsic nature.