Scanning Auger microscopy: Resolution in time, energy and space

Abstract

AbstractFor the examination of dynamic experiments using scanning Auger microscopy, it is important to achieve optimum resolution in time, energy and space. For example, to study a solidification front moving through a pool of molten metal, time resolution is necessary to allow rapid analysis at the point of freezing (allowing perhaps compositional data to be included on a phase diagram), spatial resolution should be good enough to allow accurate positioning of the electron beam on the front, and energy resolution is needed to distinguish between elements and to determine chemical state information (if it is available).This work examines a series of pure metal standards using a V.G. Scientific MA 500—a high resolution scanning Auger microscope with a hemispherical analyser. This instrument allows spectra with good signal to noise ratios to be acquired in the pulse counted mode, acquisition being totally computer controlled. Hence the effect of spectrometer variables upon pulse counted spectra has been determined by analysing the standard metals under a wide range of conditions. It has proven possible in a number of cases, to derive relationships between the spectrometer conditions (which are under operator control) and the resultant spectra. From these relationships ‘resolution diagrams’ may be constructed, which define the acquisition conditions necessary to achieve the chosen resolution in any of its three modes. It is felt that the approach used in the construction of such diagrams could be used for any spectrometer configuration.