Filtern
Erscheinungsjahr
- 2011 (2) (entfernen)
Dokumenttyp
- Zeitschriftenartikel (2) (entfernen)
Sprache
- Englisch (2)
Referierte Publikation
- ja (2)
Schlagworte
- (mu-)XRF (2) (entfernen)
Simple procedures for specifying and checking the performance of energy dispersive X-ray spectrometers (EDS) have been since 2002 available in form of the international standard ISO 15632:2002 [1]. When specifying their spectrometers all major EDS manufacturers refer meanwhile to this standard. Main spectrometer parameters such as energy resolution can be determined as recommended in there. Just several years ago the Si-Li detector has been the mostly widespread type of detector. Since four-five years, silicon drift detector (SDD) EDS providing comparable (in many cases even better) energy resolutions at much higher count rates than the conventional Si-Li’s have got the breakthrough on the market.
It is a latent wish of any SEM/EDS (scanning electron microscope with an energy dispersive spectrometer) analyst to “see more” of the analyzed specimen, i.e. to improve the existing analytical figures of merit.
One key issue are the relatively poor limits of detection (not below 0.1 mass-%) provided by energy dispersive X-ray spectrometry (EDX) with the conventional electron excitation (ED-EPMA). This is a consequence of relatively low peak-to-background ratios and reduced energy resolution when compared to wavelength dispersive spectrometry (WD-EPMA). Recent technological developments make possible to equip the SEM with a wavelength dispersive spectrometer (WDS), so that
significantly better energy resolution can be attained. Also a relative new product that can be easily attached to a SEM/EDS system is a micro-focus X-ray source. Hence, it is possible to perform (micro-focus) X-ray fluorescence spectrometry (μ-XRF) and take advantage of the enhanced peak-to-background ratios (well suited for trace analysis). However, there are also some disadvantages: an increased measurement time and excitation with a high current in the 10s of nA range are usually required for WDS. μ-XRF provides more bulk information and poor limits of detection for light elements. By combining the advantages of these analytical techniques “seeing more” becomes possible.