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Search Publications by: Nicholas Ritchie (Fed)

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Displaying 1 - 25 of 37

The hazard of UV-induced oxidation to solar-viewing spacecraft optics

March 2, 2023
Charles S. Tarrio, Robert F. Berg, Thomas B. Lucatorto, Dale E. Newbury, Nicholas Ritchie, Andrew Jones, Frank Eparvier
The two most prevalent outgas contaminants on satellites are organic molecules and water vapor. Adsorbed organic molecules can degrade a solar-viewing instrument when they are cracked by ultraviolet radiation (UV) and become a light-absorbing layer of

Quantitative Electron-Excited X-ray Microanalysis with Low Energy L-Peaks

August 12, 2021
Dale E. Newbury, Nicholas Ritchie
Quantitative electron-excited X-ray microanalysis that follows the standards-based intensity ratio method produces accurate results and an analytical total near unity based upon extensive testing on known materials. This paper investigates a significant

Proposal: Let's Develop a Community Consensus K-ratio Database

August 30, 2020
Nicholas Ritchie, Dale E. Newbury, John Fournelle, Aurelien Moy, Heather Lowers, Anette von der Handt, Paul Carpenter, Emma Bullock, John Donovan
The electron excited microanalysis community is increasingly running into the limitations of its ability to derive accurate an composition from measured x-ray intensities. Many of these limitations could be mitigated if the standard matrix correction

Embracing Uncertainty: Modeling Uncertainty in EPMA - Part I

May 21, 2020
Nicholas Ritchie
This is the first in a series of articles which present a new framework for computing the uncertainty in electron excited X-ray microanalysis measurements. This article will discuss the framework and apply it to a handful of simple but useful sub

Reference Material 8634: Ethylene Tetrafluoroethylene for Particle Size Distribution and Morphology

May 1, 2019
Dean C. Ripple, Srivalli Telikepalli, Kristen L. Steffens, Michael J. Carrier, Christopher B. Montgomery, Nicholas W. Ritchie, John Lu
Reference Material (RM) 8634 is a NIST particle standard produced from abraded ethylene tetrafluoroethylene (ETFE), a chemically inert polymer, that will help standardize and allow more accurate monitoring of subvisible proteinaceous particles in

Solidification of Ni-Re Peritectic Alloys

February 4, 2019
William J. Boettinger, Dale E. Newbury, Nicholas W. Ritchie, Maureen E. Williams, Ursula R. Kattner, Eric Lass, Kil-Won Moon, Michael B. Katz
Differential thermal analysis (DTA) and microstructural and microprobe measurements of DTA and as-cast Ni-Re alloys with compositions between 0.20 and 0.44 mass fraction Re provide information to resolve differences in previously published Ni-Re phase

Chemical Compound Classification by Elemental Signatures in Castle Dust Using SEM Automated X-ray Particle Analysis

August 1, 2018
Diana Ortiz-Montalvo, Edward P. Vicenzi, Nicholas W. Ritchie, Carol A. Grissom, Richard A. Livingston, Zoe Weldon-Yochim, Joseph M. Conny, Scott A. Wight
Discoloration on the Smithsonian Institution Building and Enid A. Haupt Garden gateposts was recently revealed to be related to a Mn enriched rock varnish. Mn does not appear to be derived locally from the building stone; therefore, its source is likely

An Iterative Qualitative - Quantitative Sequential Analysis Strategy for Electron-Excited X-ray Microanalysis with Energy Dispersive Spectrometry: Finding the Unexpected Needles in the Peak Overlap Haystack

June 20, 2018
Dale E. Newbury, Nicholas Ritchie
When analyzing an unknown by electron-excited energy dispersive X-ray spectrometry with the entire periodic table possibly in play, how does the analyst discover minor and trace constituents when their peaks are overwhelmed by the intensity of an

EDS Microanalysis: Pushing the Limits

June 1, 2018
Nicholas Ritchie, Dale E. Newbury, Michael J. Mengason, Heather Lowers
It is a great time to be a microanalyst. After a few decades of incremental progress in energy dispersive X-ray spectrometry (EDS), the last decade has seen the accuracy and precision surge forward. Today, the question is not whether EDS is generally

SEM/EDS Trace Analysis: Limits Imposed by Fluorescence of the Detector

August 4, 2017
Dale E. Newbury, Nicholas W. Ritchie, Michael J. Mengason, Keana C. Scott
Elemental trace analysis by electron-excited x-ray spectrometry performed in the scanning electron microscope (SEM) with energy dispersive x-ray spectrometry (EDS) can reach a limit of detection of 0.0005 mass fraction for many elements. Exceptions include

Efficient Simulation of Secondary Fluorescence via NIST DTSA-II Monte Carlo

March 17, 2017
Nicholas Ritchie
Secondary fluorescence, the final term in the familiar matrix correction triumvirate Z·A·F, is the most challenging for Monte Carlo models to simulate. In fact, only two implementations of Monte Carlo models commonly used to simulate electron probe x-ray

Certification of New Standard Reference Material 2806b Medium Test Dust in Hydraulic Oil

December 19, 2016
Robert A. Fletcher, Nicholas W. Ritchie, David S. Bright, James J. Filliben, William F. Guthrie
A new material has been certified to become Standard Reference Material (SRM) 2806b - Medium Test Dust in Hydraulic Fluid. SRM 2806b consists of a trace polydisperse, irregularly shaped mineral dust particles suspended in hydraulic fluid. The certified

Microscopy and Microanalysis of Individual Collected Particles- Chapter 10

July 5, 2011
Robert A. Fletcher, Nicholas W. Ritchie, Ian M. Anderson, John A. Small
This chapter describes microscopy and microanalysis techniques used for the characterization of collected, individual particles in a variety of instruments. The instruments discussed are the light microscope, electron microscopes (both scanning and