Laboratory XPS Imaging:

Abstract

Laboratory XPS imaging has changed dramatically with the most recent generation of XPS instrumentation. Image acquisition times of seconds to minutes have transformed XPS imaging from a novelty to a routine analysis method. This transition has been facilitated by the development of focused x-ray sources, new analyzers and improved detection systems. Methods of image acquisition, and current capabilities will be demonstrated, and speculations about future developments will be offered. This enhanced surface chemical characterization of heterogeneous samples comes at the cost of increasing complexity in the XPS data sets acquired. For example, in a spectra-from-images experiment, images are acquired as a function of binding energy. The resulting multi-spectral imaging data set is a complex data structure, requiring more sophisticated analysis methods than visual inspection, if the data are to be interpreted effectively. We will discuss a variety of multivariate analysis methods that can be utilized to assist in the evaluation of large data sets New opportunities for multi-technique correlations also arise from the improved spatial resolution and decreased data acquisition times. A variety of techniques, including FTIR, AFM and TOF-SIMS have spatial resolutions comparable to, or better than XPS, making correlative analyses possible. Examples demonstrating the additional information obtained when XPS measurements are combined with imaging FTIR or AFM will be shown. Considerations in comparison of images of very different spatial resolutions will be discussed.