Hemispherical Analyser with 2-D PSD for Zero-degree Auger Projectile Spectroscopy

Abstract

Details of a new high gain zero-degree Auger projectile electron spectrograph using a hemispherical analyser and a 2-dimensional position sensitive detector (PSD) with multichannel plates and a resistive anode encoder are presented. A four-element lens mounted at the entrance of the analyser, provides a virtual slit for the incoming electrons by focusing them while at the same time decelerating them to improve their energy resolution. Electrons enter through an aperture at a position R0 which is displaced (along the energy dispersion axis) with respect to the commonly used central entrance position at ½(R1 + R2). The analyser has an acceptance energy range of 20% and an energy resolution of 0.9%. An ion-optics trajectory simulation indicates improved focusing properties for this off-center position thus avoiding the need for cumbersome fringing field correction schemes. Test measurements of high resolution projectile Auger spectra produced in 21.7 MeV collisions of F8+ and F7+ projectiles with H2 and He are presented.