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Search Publications by: Nicholas Ritchie (Fed)

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Displaying 26 - 50 of 76

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

May 1, 2019
Author(s)
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
Author(s)
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
Author(s)
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
Author(s)
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
Author(s)
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
Author(s)
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
Author(s)
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
Author(s)
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