Paper AS-MoA9
Methods for X-ray Photoelectron Spectromicroscopy

Monday, October 20, 2008, 4:40 pm, Room 207

Fast parallel XPS imaging of surfaces has been commercially available for more than a decade. During this time numerous examples of both elemental and chemical state images have been published. X-ray photoelectron imaging has become a routine technique for the determination of lateral distribution of elements and chemical species at the surface and capable of a lateral resolution of <3µm over areas of several millimetres. More recently the spherical mirror analyser (SMA), used for energy selection in XPS imaging applications, has been combined with the delay line detector (DLD), a two-dimensional, pulse counting electron detector. This detector has allowed the realisation of quantitative surface chemical state microscopy by XPS. To generate such information requires the acquisition of a several images, or a series of images, incremented in energy so that each pixel contains photoelectron intensity information as a function of photoelectron energy. Fast counting electronics enable the detector to collect over 65,500 pixels per image. The different methods of collecting the necessary data and the application of multivariate analysis to analyse the information content of the data and as a tool for noise reduction in individual images or spectra will be described. Methods for obtaining the maximum information from the minimum acquisition time will also be discussed. The application of the various approaches to a variety of diverse samples will be presented.