| AVS 62nd International Symposium & Exhibition | |
| Applied Surface Science | Wednesday Sessions |
| Session AS+SS-WeA |
| Session: | Characterization of Buried Interfaces |
| Presenter: | Sarah Coultas, Kratos Analytical Limited, UK |
| Authors: | S.J. Coultas, Kratos Analytical Limited, UK J.D.P. Counsell, Kratos Analytical Limited, UK S.J. Hutton, Kratos Analytical Limited, UK A.J. Roberts, Kratos Analytical Limited, UK C.J. Blomfield, Kratos Analytical Limited, UK |
| Correspondent: | Click to Email |
High energy X-ray sources have been used in XPS analysis for some time to access more core-levels and probe deeper into the sample surface. Lab based sources such as Zr and Ti have been offered in the past but the broad X-ray line widths produced by such sources limit their applications for chemical analysis. This problem is mitigated by the use of an Ag Lα X-ray source. The source energy is 2984 eV, conveniently approximately twice that of Al Kα, hence the same quartz crystal mirror may be used to monochromate the Ag Lα X-ray line producing a narrow, high energy source of X-rays for XPS. Modern X-ray photoelectron spectrometers may be fitted with automated Al / Ag X-ray monochromators which greatly improve the usability of Ag Lα X-rays allowing Al and Ag X-ray generated spectra to be recorded from the same sample as part of automated data acquisition. Highlights of the source’s characteristics include:
• Good sensitivity and energy resolution provide useful chemical information
• Enhanced surface compositional information from approximately twice the analytical depth as Al Kα radiation for same core line
• Higher excitation energy allows deeper core levels and additional Auger lines to be explored
• Large energy range of Ag Lα allows exploitation of “depth dimension” for surface segregation studies
Here we investigate the practical uses of these characteristics. This includes using the Auger parameter for aluminium and silicon containing compounds where the higher energy radiation can excite the 1s core lines and the KLL Auger series. Earlier studies [1] have shown the usefulness of higher excitation energies in elucidating structure via Auger parameters.
We also illustrate the usefulness of Ag Lα as an additional tool for the surface analyst by way of examples of spectroscopy, ARXPS, depth profiling and imaging.
1. References[1] J.E. Castle, L.B. Hazell & RH West, J. Electron Spectrosc. Relat. Phenom. ., 1979, 16, 97