A high luminosity UHV orange type magnetic spectrometer developed for depth selective Mössbauer spectroscopy

Abstract

An improved orange type magnetic spectrometer for the detection of electrons up to 45 keV has been constructed. This spectrometer combines a particularly high transmission of typically 20% of 4π with a relative momentum resolution in the order of 0.1%. At 1% relative momentum resolution a possible source diameter of 10 mm provides a high luminosity. Furthermore, the instrument has been optimised for high resolution over a broad focal area such that the simultaneous registration of several energy channels in an interval of ΔE el E el = ±4% around the average energy setting E el increases the effective transmission by at least a factor of 5. The UHV orange spectrometer has been constructed for depth selective Mössbauer spectroscopy. But it possesses features that are useful for other applications. For instance the combination with an electrostatic retardation in the vicinity of the sample provides the possibility of an even higher energy resolution of electrons with primary energies of some keV. Due to the spatial freedom around the sample several methods like DCEMS, AES and XPS may be integrated in one experimental set-up. The coincident detection of emitted X-rays may be considered. The Auger- and photo electron spectrum of a gold layer that has been irradiated by γ-quanta and X-rays of a 57Co-source will be shown for energies up to 45 keV. The particularly high quality of the UHV orange spectrometer for Depth Selective Conversion Electron Mössbauer Spectroscopy (DCEMS) with regard to detection efficiency and depth profile information is demonstrated on an ion implanted sample. Also non-enriched samples can now be analysed in reasonable time.