Dale E. Newbury

National Institute of Standards and Technology, Maryland, United States

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Publications (217)275.33 Total impact

  • Dale E. Newbury · Nicholas W. M. Ritchie ·
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    ABSTRACT: A scanning electron microscope with a silicon drift detector energy-dispersive X-ray spectrometer (SEM/SDD-EDS) was used to analyze materials containing the low atomic number elements B, C, N, O, and F achieving a high degree of accuracy. Nearly all results fell well within an uncertainty envelope of ±5% relative (where relative uncertainty (%)=[(measured−ideal)/ideal]×100%). Quantification was performed with the standards-based “k-ratio” method with matrix corrections calculated based on the Pouchou and Pichoir expression for the ionization depth distribution function, as implemented in the NIST DTSA-II EDS software platform. The analytical strategy that was followed involved collection of high count (>2.5 million counts from 100 eV to the incident beam energy) spectra measured with a conservative input count rate that restricted the deadtime to ~10% to minimize coincidence effects. Standards employed included pure elements and simple compounds. A 10 keV beam was employed to excite the K- and L-shell X-rays of intermediate and high atomic number elements with excitation energies above 3 keV, e.g., the Fe K-family, while a 5 keV beam was used for analyses of elements with excitation energies below 3 keV, e.g., the Mo L-family.
    Microscopy and Microanalysis 09/2015; 21(5):1-14. DOI:10.1017/S1431927615014993 · 1.88 Impact Factor
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    Dale E. Newbury · Nicholas W. M. Ritchie ·
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    ABSTRACT: Electron-excited X-ray microanalysis performed in the scanning electron microscope with energy-dispersive X-ray spectrometry (EDS) is a core technique for characterization of the microstructure of materials. The recent advances in EDS performance with the silicon drift detector (SDD) enable accuracy and precision equivalent to that of the high spectral resolution wavelength-dispersive spectrometer employed on the electron probe microanalyzer platform. SDD-EDS throughput, resolution, and stability provide practical operating conditions for measurement of high-count spectra that form the basis for peak fitting procedures that recover the characteristic peak intensities even for elemental combination where severe peak overlaps occur, such PbS, MoS2, BaTiO3, SrWO4, and WSi2. Accurate analyses are also demonstrated for interferences involving large concentration ratios: a major constituent on a minor constituent (Ba at 0.4299 mass fraction on Ti at 0.0180) and a major constituent on a trace constituent (Ba at 0.2194 on Ce at 0.00407; Si at 0.1145 on Ta at 0.0041). Accurate analyses of low atomic number elements, C, N, O, and F, are demonstrated. Measurement of trace constituents with limits of detection below 0.001 mass fraction (1000 ppm) is possible within a practical measurement time of 500 s.
    Journal of Materials Science 09/2015; 50(2). DOI:10.1007/s10853-014-8685-2 · 2.37 Impact Factor
  • Nicholas W. M. Ritchie · Dale E. Newbury ·

    Microscopy and Microanalysis 08/2014; 20(S3):696-697. DOI:10.1017/S1431927614005200 · 1.88 Impact Factor
  • Dale E. Newbury · Nicholas W. M. Ritchie ·

    Microscopy and Microanalysis 08/2014; 20(S3):702-703. DOI:10.1017/S1431927614005236 · 1.88 Impact Factor
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    Aaron Shugar · Michael Notis · Dale Newbury · Nicholas Ritchie ·
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    ABSTRACT: A Moche cast copper alloy object was investigated with focus on three main areas: the alloy composition, the casting technology, and the corrosion process. This complex artifact has thin connective arms between the body and the head, a situation that would be very difficult to cast. The entire artifact was mounted and polished allowing for complete microstructural and microchemical analysis, providing insight into the forming technology. In addition, gigapixel x-ray spectrum imaging was undertaken to explore the alloy composition and the solidification process of the entire sample. This process used four 30 mm 2
    MRS Fall Meeting 2013; 01/2014
  • Dale E. Newbury · Nicholas W. M. Ritchie ·
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    ABSTRACT: Elemental mapping at the microstructural level by scanning electron microscopy (SEM) with energy dispersive X-ray spectrometry (EDS), while widely applied in science, engineering, and technology, has been limited in performance by the throughput of the lithium-drifted silicon detector [Si(Li)-EDS] which restricts the number of X-ray counts measured per image pixel. The emergence of the silicon drift detector (SDD-EDS) has greatly extended the X-ray throughput, by a factor of 25 to 70 for the same spectral resolution. This improved performance enables practical X-ray spectrum imaging (XSI), in which a complete X-ray spectrum is recorded at each image pixel. By performing complete quantitative corrections for background, peak overlap, and matrix effects to each pixel spectrum, full compositional mapping can be achieved. Various elemental mapping collection strategies are described, including quantitative mapping at the major (concentration C > 0.1 mass fraction), minor (0.01 ≤ C ≤ 0.1), and trace (C < 0.01) constituent levels, extreme pixel density (gigapixel) mapping, rapid mapping (in 10 seconds or less), and high spatial resolution mapping with the thermal field emission gun scanning electron microscope.
    Journal of Analytical Atomic Spectrometry 06/2013; 28(7):973-988. DOI:10.1039/C3JA50026H · 3.47 Impact Factor
  • Dale E. Newbury · Nicholas W. M. Ritchie ·
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    ABSTRACT: The typical strategy for analysis of a microscopic particle by scanning electron microscopy/energy dispersive spectrometry x-ray microanalysis (SEM/EDS) is to use a fixed beam placed at the particle center or to continuously overscan to gather an “averaged” x-ray spectrum. While useful, such strategies inevitably concede any possibility of recognizing microstructure within the particle, and such fine scale structure is often critical for understanding the origins, behavior, and fate of particles. Elemental imaging by x-ray mapping has been a mainstay of SEM/EDS analytical practice for many years, but the time penalty associated with mapping with older EDS technology has discouraged its general use and reserved it more for detailed studies that justified the time investment. The emergence of the high throughput, high peak stability silicon drift detector (SDD-EDS) has enabled a more effective particle mapping strategy: “flash” x-ray spectrum image maps can now be recorded in seconds that capture the spatial distribution of major (concentration, C > 0.1 mass fraction) and minor (0.01 ≤ C ≤ 0.1) constituents. New SEM/SDD-EDS instrument configurations feature multiple SDDs that view the specimen from widely spaced azimuthal angles. Multiple, simultaneous measurements from different angles enable x-ray spectrometry and mapping that can minimize the strong geometric effects of particles. The NIST DTSA-II software engine is a powerful aid for quantitatively analyzing EDS spectra measured individually as well as for mapping information (available free for Java platforms at: http://www.cstl.nist.gov/div837/837.02/epq/dtsa2/index.html).
    SPIE Defense, Security, and Sensing; 05/2013
  • Dale E Newbury · Nicholas W M Ritchie ·
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    ABSTRACT: Scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS) is a widely applied elemental microanalysis method capable of identifying and quantifying all elements in the periodic table except H, He, and Li. By following the "k-ratio" (unknown/standard) measurement protocol development for electron-excited wavelength dispersive spectrometry (WDS), SEM/EDS can achieve accuracy and precision equivalent to WDS and at substantially lower electron dose, even when severe X-ray peak overlaps occur, provided sufficient counts are recorded. Achieving this level of performance is now much more practical with the advent of the high-throughput silicon drift detector energy dispersive X-ray spectrometer (SDD-EDS). However, three measurement issues continue to diminish the impact of SEM/EDS: (1) In the qualitative analysis (i.e., element identification) that must precede quantitative analysis, at least some current and many legacy software systems are vulnerable to occasional misidentification of major constituent peaks, with the frequency of misidentifications rising significantly for minor and trace constituents. (2) The use of standardless analysis, which is subject to much broader systematic errors, leads to quantitative results that, while useful, do not have sufficient accuracy to solve critical problems, e.g. determining the formula of a compound. (3) EDS spectrometers have such a large volume of acceptance that apparently credible spectra can be obtained from specimens with complex topography that introduce uncontrolled geometric factors that modify X-ray generation and propagation, resulting in very large systematic errors, often a factor of ten or more. SCANNING 00: 1-28, 2012. Published 2012 Wiley Periodicals, Inc.†
    Scanning 05/2013; 35(3). DOI:10.1002/sca.21041 · 1.89 Impact Factor
  • Nicholas William Miller Ritchie · Dale E. Newbury ·
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    ABSTRACT: It has been over 60 years since Castaing introduced the technique of electron probe x-ray microanalysis (EPMA) yet the community remains unable to quantify some of the largest terms in the technique's uncertainty budget. Historically, the EPMA community has assigned uncertainties to its measurements which reflect the measurement precision portion of the uncertainty budget and omitted terms related to the measurement accuracy. Yet, in many cases, the precision represents only a small fraction of the total budget. This paper addresses the shortcoming by considering two significant sources of uncertainty in the quantitative matrix correction models - the mass absorption coefficient, [μ⁄ρ], and the backscatter coefficient, η. Understanding the influence of these sources provides insight into the utility of EPMA measurements and, equally important, it allows practitioners to develop strategies to optimize measurement accuracy by minimizing the influence of poorly known model parameters.
    Analytical Chemistry 10/2012; 84(22). DOI:10.1021/ac301843h · 5.64 Impact Factor
  • Nicholas W.M. Ritchie · Dale E Newbury · Jeffrey M Davis ·
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    ABSTRACT: The accuracy and precision of X-ray intensity measurements with a silicon drift detector (SDD) are compared with the same measurements performed on a wavelength dispersive spectrometer (WDS) for a variety of elements in a variety of materials. In cases of major (>0.10 mass fraction) and minor (>0.01 mass fraction) elements, the SDD is demonstrated to perform as well or better than the WDS. This is demonstrated both for simple cases in which the spectral peaks do not interfere (SRM-481, SRM-482, and SRM-479a), and for more difficult cases in which the spectral peaks have significant interferences (the Ba L/Ti K lines in a series of Ba/Ti glasses and minerals). We demonstrate that even in the case of significant interference high count SDD spectra are capable of accurately measuring Ti in glasses with Ba:Ti mass fraction ratios from 2.7:1 to 23.8:1. The results suggest that for many measurements wavelength spectrometry can be replaced with an SDD with improved accuracy and precision.
    Microscopy and Microanalysis 07/2012; 18(4):892-904. DOI:10.1017/S1431927612001109 · 1.88 Impact Factor
  • N. W. Ritchie · D. E. Newbury · S. Leigh ·

    Microscopy and Microanalysis 07/2012; 18(S2):1006-1007. DOI:10.1017/S1431927612006885 · 1.88 Impact Factor
  • D. E. Newbury · N. W. Ritchie ·

    Microscopy and Microanalysis 07/2012; 18(S2):1010-1011. DOI:10.1017/S1431927612006903 · 1.88 Impact Factor
  • D. E. Newbury · N. W. Ritchie ·

    Microscopy and Microanalysis 07/2012; 18(S2):1004-1005. DOI:10.1017/S1431927612006873 · 1.88 Impact Factor
  • Dale E. Newbury · Nicholas W. M. Ritchie ·
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    ABSTRACT: Scanning electron microscopy with energy dispersive x-ray spectrometry (SEM/EDS) is a powerful and flexible elemental analysis method that can identify and quantify elements with atomic numbers > 4 (Be) present as major constituents (where the concentration C > 0.1 mass fraction, or 10 weight percent), minor (0.01<= C <= 0.1) and trace (C < 0.01, with a minimum detectable limit of ~+/- 0.0005 - 0.001 under routine measurement conditions, a level which is analyte and matrix dependent ). SEM/EDS can select specimen volumes with linear dimensions from ~ 500 nm to 5 μm depending on composition (masses ranging from ~ 10 pg to 100 pg) and can provide compositional maps that depict lateral elemental distributions. Despite the maturity of SEM/EDS, which has a history of more than 40 years, and the sophistication of modern analytical software, the method is vulnerable to serious shortcomings that can lead to incorrect elemental identifications and quantification errors that significantly exceed reasonable expectations. This paper will describe shortcomings in peak identification procedures, limitations on the accuracy of quantitative analysis due to specimen topography or failures in physical models for matrix corrections, and quantitative artifacts encountered in xray elemental mapping. Effective solutions to these problems are based on understanding the causes and then establishing appropriate measurement science protocols. NIST DTSA II and Lispix are open source analytical software available free at www.nist.gov that can aid the analyst in overcoming significant limitations to SEM/EDS.
    Proceedings of SPIE - The International Society for Optical Engineering 05/2012; 8378:2-. DOI:10.1117/12.912770 · 0.20 Impact Factor
  • Nicholas W.M. Ritchie · Dale E Newbury · Abigail P Lindstrom ·
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    ABSTRACT: Artifacts are the nemesis of trace element analysis in electron-excited energy dispersive X-ray spectrometry. Peaks that result from nonideal behavior in the detector or sample can fool even an experienced microanalyst into believing that they have trace amounts of an element that is not present. Many artifacts, such as the Si escape peak, absorption edges, and coincidence peaks, can be traced to the detector. Others, such as secondary fluorescence peaks and scatter peaks, can be traced to the sample. We have identified a new sample-dependent artifact that we attribute to Compton scattering of energetic X-rays generated in a small feature and subsequently scattered from a low atomic number matrix. It seems likely that this artifact has not previously been reported because it only occurs under specific conditions and represents a relatively small signal. However, with the advent of silicon drift detectors and their utility for trace element analysis, we anticipate that more people will observe it and possibly misidentify it. Though small, the artifact is not inconsequential. Under some conditions, it is possible to mistakenly identify the Compton scatter artifact as approximately 1% of an element that is not present.
    Microscopy and Microanalysis 11/2011; 17(6):903-10. DOI:10.1017/S1431927611012189 · 1.88 Impact Factor
  • R. B. Marinenko · R. L. Myklebust · D. S. Bright · D. E. Newbury ·
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    ABSTRACT: SUMMARYA new, simplified procedure for correcting the defocusing observed in low-magnification digital maps obtained with the electron microprobe using wavelength spectrometers is described. This procedure uses a wavelength scan of the analysed element and the geometric relationship between the specimen and the diffracting crystal to calculate a model of a standard map, which is subsequently used in the quantification of each pixel of the unknown map. The results of this new procedure are compared with the earlier method of using an experimentally obtained standard map.
    Journal of Microscopy 08/2011; 155(2):183 - 198. DOI:10.1111/j.1365-2818.1989.tb02881.x · 2.33 Impact Factor
  • D. B. Williams · R. Levi-Setti · J. M. Chabala · D. E. Newbury ·
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    ABSTRACT: Samples of aluminium-lithium alloys have been observed by scanning ion microscopy and analysed by secondary ion mass spectrometry. The high signal-to-noise ratio of the positive secondary lithium ion opens up the possibility of both high resolution imaging and microanalysis of lithium distributions in aluminium and other materials. Some of the problems encountered due to sample preparation are discussed and ion images of both the artefacts and the true lithium distribution are shown.
    Journal of Microscopy 08/2011; 148(3):241 - 252. DOI:10.1111/j.1365-2818.1987.tb02870.x · 2.33 Impact Factor
  • N. W. M. Ritchie · J. Davis · D. E. Newbury ·

    Microscopy and Microanalysis 07/2011; 17:556-557. DOI:10.1017/S1431927611003655 · 1.88 Impact Factor
  • D. Newbury · N. Ritchie ·

    Microscopy and Microanalysis 07/2011; 17:558-559. DOI:10.1017/S1431927611003667 · 1.88 Impact Factor
  • A. Lindstrom · N. Ritchie · D. Newbury ·

    Microscopy and Microanalysis 07/2011; 17:1854-1855. DOI:10.1017/S1431927611010142 · 1.88 Impact Factor

Publication Stats

2k Citations
275.33 Total Impact Points


  • 1987-2014
    • National Institute of Standards and Technology
      • • Materials Measurement Science Division
      • • Analytical Chemistry Division
      • • Material Measurement Laboratory (MML)
      • • Microanalysis Research Group
      • • Quantum Electronics and Photonics Division
      Maryland, United States
  • 1998
    • The University of Tennessee Medical Center at Knoxville
      Knoxville, Tennessee, United States
  • 1970
    • University of Oxford
      Oxford, England, United Kingdom