ANGLE RESOLVED PHOTOEMISSION USING A TOROIDAL ENERGY ANALYZER

Toroidal analysers may be designed so that all the electrons emitted in a selected plane with a particular energy may be detected in parallel using a position sensitive detector. Thus, all off-normal ARUPS data may be acquired in the time it would take a conventional analyser to obtain only the normal emission data. Experience with such an analyser is described, particular attention being paid to the determination of bandstructure using fixed photon energy data. Studies of InGaAs are used to illustrate the suitability of the instrument for synchrotron radiation measurements. The instrument also makes possible novel experiments such as angle resolved constant initial state Spectroscopy; we show an example from GaAs (110). The surface state on Cu (111) is used to demonstrate the high angular resolution of this analyser. © 1990.