A study of the silver X-ray source for photoelectron spectroscopy.

A novel x-ray anode for electron spectroscopy is investigated for application in the surface analysis field, monochromatic Ag Lalpha (hnu =2984. 3eV), its energy being capable of exciting 1s electrons up to chlorine in the periodic table. Resolution available with this source is satisfactory, with a limitation of approximately 1. 3eV. An increase in sensitivity is achieved for those peaks in the range 1500-3000BE, whilst there is no serious reduction within the conventional XPS energy range. The agreement between experimental sensitivity factors and theoretical cross-section values is good, allowing the transmission function for the VG ESCA3 Mkll spectrometer to be confirmed constant from 0-3000eV. A comprehensive investigation of the LEG51 electron flood gun preceded its successful application for the charge neutralisation of insulating materials. This allowed the application of this source to such materials as chlorides, pertinent to the breakdown in passivity on stainless steels, and silicon compounds, involving thermal oxides on silicon of interest to the microchip industry, zeolites for catalysis in the petrochemical industry and siloxane copolymers for the opthalmic industry. The ability to excite the 1s orbital, together with the 2p and KLL Auger lines, affords calculation of Auger parameters and extra-atomic relaxation energies for the accurate description of the chemical environment of a particular chemical species. A method for internal energy referencing is investigated, involving the vaccum-deposition of Au, Cu and Pt metals. This allows the measurement of photoelectron binding energies to an accuracy of +/-0.1-0.2eV for insulating materials, when referenced to the vacuum level