On the Correspondence of the Experimental EEL Spectra with the Electron Structure of Tungsten

Abstract

In the previous paper [7] we have directly compared the experimental Electron Energy Loss (EEL) spectra with both the theoretical bulk density-of-states (BDOS) and surface density-of-states (SDOS) functions for tungsten. On the base of the ILEED intensity calculations we have estimated to what extend an EEL spectrum measured at some value of the primary electron energy EP , should correspond either to the SDOS or to the BDOS. Also, the angular acceptance of a CMA has been used to separate the EEL spectra measured as a function of Ep which corresponded either to the [001] direction or to the [011] in parallel to the studied (001) surface. In the present paper we propose a procedure which combines the Electron Energy Loss Spectra (EELS) simulation method based on Bauer's theory [1, 2] and the inelastic low energy diffraction (ILEED). If the standard simulation procedure is applied for tungsten an ambiguity would arise because the DOS function is very anisotropic and varies as a function of both the direction along the surface and the depth considered within several atomic layers. The application of ILEED has supplemented the simulation procedure with the method which identifies both the correspondence of a reciprocal-lattice vector to a measured EEL spectrum and the localization of a studied electron structure with regard to the distance from the surface. PACS numbers: 79.20.Fv, 61.80.Mk, 82.65.-i