Chapter/Index: Introduction | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Appendix
| The sensitivity of X-ray detection drops off at the high-energy end (Figure 2357), for instance, at energies greater than 20 keV, the Si (Li) crystal (typically 3-5 mm thick) becomes transparent. This is not important in an SEM operated at 30 keV because high-energy X rays is not excited. But in a TEM operated at high voltages (e.g. ≥ 100 keV), the ability to detect hard X rays would be severely limited.
Figure 2357. Comparison between the detection efficiencies of Si(Li) and SDD detectors. Note that Ge-based EDS detectors are able to detect very high energy X rays, e.g. gold (Au) Kα (69 keV).
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