Abstract: A charged particle energy analyser has a magnetic lens such as a snorkel-type lens and a source for directing ionising radiation onto a specimen causing charged particles to be emitted from its surface. The specimen is immersed in the magnetic imaging field of the magnetic lens so that particles having energies in a predetermined energy range are brought to a focus, the energies of the focussed particles being analysed by an energy analyser. An electrode arrangement is provided for enabling the magnetic imaging field of the magnetic lens to utilise unfocussed particles to cause charge neutralisation of the specimen. Alternatively, charged particles from a source are subjected to an electric field which is transverse to the optical axis of the magnetic lens and are guided onto the specimen by the magnetic imaging field of the magnetic lens.

Abstract: A charged particle energy analyzer, such as a microscope or spectrometer, includes a magnetic immersion lens 10 to focus charged particles emitted from an irradiated specimen 5 located within the magnetic field of the lens. A collecting aperture 18 defines the area of the irradiated specimen from which charged particles can be brought to a focus in the image plane of the lens but an aperture 21 in this plane selects and defines a much smaller area of the specimen from which the received particles are passed to a suitable energy analyzing means 25. The energy analyzing means 25 then performs energy analysis of the small selected area of the specimen by imaging the small area with emitted particles of a predetermined energy, or energy scanning the particles emitted from this area, so giving a chemical analysis of the small selected area of the specimen surface.