Angle- and energy-resolved charged particle spectroscopies--a simple way
The acquisition of angular and energy distribution information is of growing importance in a number of charged particle spectroscopies used for surface studies. A simple, inexpensive method is outlined for obtaining a visual display of angular distributions containing energy distribution information in the form of color. In essence, a detector optical bandpass is varied synchronously with an energy-selecting element of a spectrometer having a visual display in order to convert the analyzed particle energy distribution to a corresponding chromatic map. The primary utility of the method would be to obtain qualitative information rapidly in those cases where the particle energy spectra have distinct and strong features or when features of interest lie at the higher-energy end. Examples of the latter are plasma loss structure in low-energy electron diffraction, electron-stimulated desorption ion angular distributions, and the higher-energy structure in ultraviolet photoelectron spectroscopy. Other applications are also considered. The practical sensitivity limit for the case of visual observation is 1.0% [I(Δ}Σ)/Itotal]. This sensitivity is not sufficient for application of the method to Auger electron spectroscopy or electron spectroscopy for chemical analysis.