A Minicomputer and Methodology for X-Ray Analysis

1979 ◽  
Vol 23 ◽  
pp. 313-316 ◽  
Author(s):  
W. Parrish ◽  
G. L. Ayers ◽  
T. C. Huang
Keyword(s):  
Thin Film ◽  
Quantitative Analysis ◽  
Data Reduction ◽  
Fluorescence Spectrometry ◽  
Small Computer ◽  
X Ray ◽  
Fundamental Parameters ◽  
Profile Fitting ◽  
Fitting Method ◽  
Integrated Intensities

AbstractThis paper outlines the use of an IBM Series/1 small computer for instrument automation and data reduction for X-ray polycrystalline diffractometry and wavelength dispersive X-ray fluorescence spectrometry. The profile fitting method is used to determine 2θ, d and relative peak and integrated intensities in diffraction, and the fundamental parameters method (LAMA program) is used for quantitative analysis of bulk and thin film samples. The methods are precise and rapid.

GENEFP: a full-profile fitting program for X-ray powder patterns using the genetic algorithm

2006 ◽  
Vol 39 (4) ◽  
pp. 615-617 ◽  
Author(s):  
Zhen Jie Feng ◽  
Cheng Dong
Keyword(s):  
Genetic Algorithm ◽  
Grain Size ◽  
Least Squares ◽  
Global Extremum ◽  
X Ray ◽  
Fundamental Parameters ◽  
Profile Fitting ◽  
Full Profile ◽  
Integrated Intensities

GENEFPis a full-profile fitting program, employing a fundamental-parameters method, for Cu-target X-ray powder patterns. In this program, the Le Bail method is used to determine integrated intensities and the genetic algorithm is used to search for the proper fundamental parameters. When some parameters, such as the grain size, have large uncertainties, the genetic algorithm has an advantage over conventional least-squares methods in finding the global extremum.

Profile Fitting for Quantitative Analysis in X-Ray Powder Diffraction

1982 ◽  
Vol 26 ◽  
pp. 141-147 ◽  
Author(s):  
Walter N. Schreiner ◽  
Ron Jenkins
Keyword(s):  
Mathematical Model ◽  
Quantitative Analysis ◽  
Phase Analysis ◽  
Powder Diffraction ◽  
Quantitative Phase Analysis ◽  
X Ray ◽  
Profile Fitting ◽  
Integration Techniques ◽  
Free Parameters ◽  
Integrated Intensities

Quantitative phase analysis by powder diffractometry requires accurate measurement of the integrated intensities of the diffracted, lines. When lines are isolated and on simple backgrounds, count integration techniques work very well. However, when one or more lines overlap the line of interest, or a complex background is present, profile fitting techniques are required in order to eliminate interferences.Profile fitting involves choosing a mathematical model to represent the expected profile shapes. Experience has shown that the profile shapes obtained with a parafocusing powder diffractometer are not easily described and many models have been tried with varying degrees of success. Generally the more free parameters allowed In the model the ‘setter the fits, although, aesthetically one would like to keep the number of free parameters to a minimum.

Crystal-structure refinement by profile fitting and least-squares analysis of powder diffractometer data

1983 ◽  
Vol 16 (6) ◽  
pp. 611-622 ◽  
Author(s):  
G. Will ◽  
W. Parrish ◽  
T. C. Huang
Keyword(s):  
Least Squares ◽  
Structure Refinement ◽  
Specimen Preparation ◽  
Crystal Structure Refinement ◽  
Instrument Function ◽  
X Ray ◽  
Profile Fitting ◽  
Fitting Method ◽  
The Individual ◽  
Integrated Intensities

The refinement of crystal structures using X-ray powder data in a two-stage method is described. (1) The integrated intensities of the individual reflections are derived by a profile fitting method in which the profile shapes are accurately defined using an experimentally determined instrument function and the sum of Lorentzian curves. (2) These values are then used in a powder least-squares refinement for structure determination. The results obtained with three simple structures (silicon, quartz and corundum) gave R(Bragg) values of 0.7 to 2.5%. The necessity of correcting for preferred orientation and the importance of proper specimen preparation are also discussed.

Development of Gas Scintillation Proportional Counter

1999 ◽  
Vol 09 (03n04) ◽  
pp. 169-174
Author(s):  
N. Shigeoka ◽  
K. Mutaguchi ◽  
Y. Nakanishi ◽  
Y. Ito ◽  
T. Mukoyama ◽  
...  
Keyword(s):  
Proportional Counter ◽  
Pulse Height ◽  
Acceleration Region ◽  
X Ray ◽  
Gaussian Profile ◽  
Profile Fitting ◽  
Fitting Method

The properties of gas scintillation proportional counter are investigated for Mn K x-ray spectra. The pulse-height spectra are strongly affected by changing of the value of a potential V 2 in the acceleration region and analyzed by the Gaussian profile fitting method.

NIST SRM 2708, Zinc Sulfide Thin Film on Polycarbonate for X-Ray Fluorescence Spectrometry

1992 ◽  
Vol 36 ◽  
pp. 273-278
Author(s):  
P.A. Pella ◽  
W.R. Kelly ◽  
K.E. Murphy ◽  
E.B. Steel ◽  
S.B. Schiller
Keyword(s):  
Thin Film ◽  
Zinc Sulfide ◽  
Ion Beam ◽  
Fluorescence Spectrometry ◽  
Similar Material ◽  
Filter Media ◽  
X Ray ◽  
Sputter Deposited ◽  
Beam Instrument

NIST SRM 2708 is a thin film of zinc sulfide approximately 0.02 μm thick that was sputter deposited on polycarbonate substrates using a NIST ion-beam instrument. It is intended for the standardization of x-ray fluorescence spectrometers, especially for analysis of air particulates or similar material collected on filter media.

A Comparison of the XRF11 and EXACT Fundamental Parameters Programs when Using Filtered Direct and Secondary Target Excitation in EDXRF

1982 ◽  
Vol 26 ◽  
pp. 369-376 ◽  
Author(s):  
Ronald A. Vane
Keyword(s):  
Energy Dispersive ◽  
Fluorescence Spectrometry ◽  
X Ray ◽  
Fundamental Parameters ◽  
Secondary Target ◽  
Direct Excitation

The XRF11 program by John Criss and the EXACT program are two commercially available fundamental parameters programs for energy dispersive x-ray fluorescence spectrometry (EDXRF). These programs are both based on the same underlying equations but use different approaches to the calculations. The EXACT program assumes monochromatic excitation, and the XEF11 program models polychromatic excitation sources. There are also great differences in how the two programs approach the iterations in the calculations and in how the data from standards are used in the two programs for calibration.To produce the monochromatic excitation neeiled by the EXACT program, secondary targets have been the preferred method. But it is also possible to approximate monochromatic excitation by using filtered direct excitation. The purpose of this study is to compare the data obtained from both secondary targets and direct filtered excitation as processed through both XRF11 and EXACT.

The Application of X-Ray Fluorescence and Diffraction to the Characterization of Environmental Assessment Samples

1981 ◽  
Vol 25 ◽  
pp. 189-194
Author(s):  
Albert C. Censullo ◽  
Frank E. Briden
Keyword(s):  
Computer Program ◽  
Environmental Assessment ◽  
Technical Support ◽  
Support Staff ◽  
Fluorescence Spectrometry ◽  
X Ray ◽  
Fundamental Parameters ◽  
Technical Support Staff

The Technical Support Staff is called upon for analysis of a wide variety of sample types many of which have little sample history. However, it is usually necessary to account for all elements present. For these reasons, x-ray fluorescence spectrometry (XRF) has been a useful tool. Unfortunately, XRF requires the use of a range of standards for each element, the preparation of which could become so time consuming that the advantages of XRF would soon be diluted. Consequently, the utility of the J. W. Criss fundamental parameters computer program was evaluated for samples in which only one standard per element was used and where the standard matrix did not strictly resemble the unknown matrix. Some of the results of these tests on environmental assessment samples are reported here.

Results of quantitative analysis of Celtic glass artefacts by energy dispersive X-ray fluorescence spectrometry

2003 ◽  
Vol 58 (4) ◽  
pp. 627-633 ◽  
Author(s):  
C. Jokubonis ◽  
P. Wobrauschek ◽  
S. Zamini ◽  
M. Karwowski ◽  
G. Trnka ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Energy Dispersive ◽  
Fluorescence Spectrometry ◽  
X Ray
Sign in / Sign up

Export Citation Format

Share Document