The NiOx Test Specimen has been developed for advanced analytical TEM's equipped with X-Ray Micro Analysis
Systems (EDX) and/or Electron Energy Loss Spectrometers (EELS) to characterize instrument performance.
It consists of a 55nm layer of NiOx on a 25nm carbon support film on a 200 mesh Mo TEM grid.
The NiOx Test Specimen is valuable in at least three ways:
- When evaluating TEM's and EDX systems prior to purchase.
- Immediately after installation of the EDX detector, to check that column conditions and detector alignment are satisfactory.
- Periodically during operation of the system, to check for possible icing or hydrocarbon contamination on the detector.
The test specimen provides an Mo signal to measure stray X-rays and electrons present in the TEM column.
The NiOx film contains a known amount of a light element (oxygen) and is used for evaluation the EDX detector
response to low energy X-rays. In EELS, the oxygen and nickel ionization edges allow energy-axis calibration
and elemental-ratio measurements to be performed. It is possible to make a direct comparison of elemental analyses
obtained by EDX and EELS for a TEM equipped with both systems.
Typical EDX spectrum for a 55nm specimen of NiO on a 200-mesh Mo grid, coated with 25nm C, with the 200 keV
incident beam near the center of a grid square. The small Fe Ka: peak is generated by the microscope column
(perhaps objective pole-pieces).(reprinted with permission)
Since the nickel oxide film is a fine-grained polycrystal, it is well suited to the calibration of TEM camera length
and the correction of intermediate-lens astigmatism.
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Each specimen is packaged in an aluminum storage container #650-10 with instructions for the measurement of camera length,
evaluating the amount of stray radiation in the TEM column and its predominant character (X-rays or electrons),
for estimating the collection solid angle of the EDX detector and for determining the extent of ice or hydrocarbon
contamination on the detector. |
- Egerton RF, Cheng SC, (1994) Characterization of an analytical electron microscope with a NiO test specimen. Ultramicroscopy, 55 43-54.
- Bennett JC, Cheng SC, Egerton R, July 1994. The use of NiO test specimens in analytical electron microscopy. ICEM 13-Paris, 17-22 , 613-614.
- Bennett JC, Cheng SC, 1995. NiO test specimens for analytical electron microscopy. Round Robin results. JMSA, 1, 44, 143-149.
PELCO® Technical Notes: Evaluating an Analytical TEM with the NiOx Test Specimen (285kb pdf)