PNNL

Abstract

Many research groups have observed electron and x-ray damage on a variety of materials. It is, of course, highly desirable to take advantage of the considerable experience gained by others in observing the presence of damage. Ideally, damage processes and rates would be determined for the samples of interest on the instrument in which measurements are to be made. However, in many cases such measurements are not possible and many important speciments are one of a kind. Several compilations of damage rates are available in the literature 1,2, or from Companies 3. In most cases the data from these potentially useful data sets are not likely to directly relate to the damage rates that might be observed for other instruments. There are two related reasons for this. First there is over an order of magnitude difference between x-ray damage rates observed on instruments in current use, as reported by Yoshihara and Tanaka.4 In addition, many new instruments have higher x-ray fluxes than many older instruments. The damage rates observed in the Pacific Northwest National Laboratory (PNNL) PHI Quantum 2000, are in the lower 1/3 of the instruments reported in Reference 4 but are approximately 5 times faster than those reported by Beamson and Briggs1 in 1992 for the Scienta 300 system.