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RAP opportunity at National Institute of Standards and Technology     NIST

High Performance Energy Dispersive Electron Excited X-ray Microanalysis


Material Measurement Laboratory, Materials Measurement Science Division

opportunity location
50.64.31.C0795 Gaithersburg, MD

NIST only participates in the February and August reviews.


name email phone
Nicholas WM Ritchie 301.975.3929


With the advent of the silicon drift energy dispersive X-ray detector (SDD/EDS), enhanced opportunities for high precision and accuracy measurements have opened up[1].   Unfortunately though, few people are making full use of the increased precision and accuracy which can be achieved with these detectors.  Historically the gold standard for electron excited X-ray microanalysis has been the electron probe microanalyzer with wavelength dispersive spectrometer (EPMA/WDS).  On the other hand, energy dispersive X-ray microanalysis is often viewed as qualitative or less quantitiative than EPMA/WDS.  This need not be.  With the same level of care,  SDD/EDS can produce results with similar precision and accuracy as EPMA/WDS for a large fraction of sample types.  Furthermore, since SDD/EDS is an experimentally simpler technique than EPMA/WDS and more people own the necessary equipment, there are many opportunities to help the industrial, forensic and academic communities.  However, there are many practical impediments which need to be addressed to realize the full potential of SDD/EDS.

We work on many different aspects of the problem:

  1. Modeling X-ray measurements from incident electrons through to detected X-rays
  2. Spectrum processing (particularly low energy lines)
  3. Weights of lines and other critical physical parameter measurements
  4. Measurement optimization
  5. Matrix correction model breakdown
  6. Lack of availability of suitable standards (material and k-ratio databases)

We are open to other research topics which could assist the community to make more precise/accurate SDD/EDS measurements.

[1] Newbury, D., & Ritchie, N. (2019). Electron-Excited X-ray Microanalysis by Energy Dispersive Spectrometry at 50: Analytical Accuracy, Precision, Trace Sensitivity, and Quantitative Compositional Mapping. Microscopy and Microanalysis, 25(5), 1075-1105. doi:10.1017/S143192761901482X

key words
X-ray; Microanalysis; Electron-excited; silicon drift detector; matrix correction; Monte Carlo modeling


Citizenship:  Open to U.S. citizens
Level:  Open to Postdoctoral applicants


Base Stipend Travel Allotment Supplementation
$82,764.00 $3,000.00
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