Computer Code for Analysing X-Ray Fluorescence Spectra of Airborne Particulate Matter

1979 ◽  
Vol 23 ◽  
pp. 149-156 ◽  
Author(s):  
E.A. Drane ◽  
D.G. Rickel ◽  
W.J. Courtney ◽  
T.G. Dzubay
Keyword(s):  
Atmospheric Aerosols ◽  
Fluorescence Spectra ◽  
Pulse Height ◽  
Silicon Detector ◽  
Airborne Particulate Matter ◽  
Computer Code ◽  
Elemental Content ◽  
X Ray ◽  
Edxrf Analysis ◽  
Fluorescence Spectrometer

During recent years energy dispersive x-ray fluorescence (EDXRF) has been used to measure the elemental content of atmospheric aerosols. The code described here is used to reduce EDXRF data and determine the elemental composition of samples collected on membrane filters. The program has been specifically written for EDXRF analysis of size-fractionated aerosols collected by a dichotomous sampler.The x-ray fluorescence spectrometer used in our laboratory employs a pulsed-mode x-ray tube and a lithium-drifted silicon detector. Pulse-height spectra are produced for elements ranging in atomic number from Z = 13 to Z = 82 (corresponding to an energy range from 1.4 to 32.1 keV). Approximately uniform x-ray production is attained by producing independent spectra from three secondary targets (Ti, Mo, Sm).

Applications of a Portable Radioisotope X-Ray Fluorescence Spectrometer to Analysis of Minerals and Alloys*

1967 ◽  
Vol 11 ◽  
pp. 249-274 ◽  
Author(s):  
J. R. Rhodes ◽  
T. Furuta
Keyword(s):  
Single Channel ◽  
Scintillation Counter ◽  
Pulse Height ◽  
X Rays ◽  
X Ray ◽  
Scattering Coefficients ◽  
Finite Samples ◽  
Counting Statistics ◽  
Fluorescence Spectrometer ◽  
Sulfur In Coal

AbstractA portable, battery-operated X-ray fluorescence analyzer weighing 15 lb is described, consisting of a Nal(Tl) scintillation-counter probe and an electronic unit with a single-channel pulse-height analyzer and reversible scaler. Radioisotope X-ray sources are used for excitation of the sample and, where necessary, balanced filters for resolution of neighboring characteristic X-rays. Emphasis has been placed on designing and producing an instrument that is easy and convenient to operate in laboratory, factory, or field conditions and that can equally well be used to measure extended surfaces, such as rock faces, or finite samples in the form of powders, briquettes, or liquids. The feasibility of the following analyses has been studied by using for each determination the appropriate radioisotope source and filters: sulfur in coal; calcium and iron in cement raw mix; copper in copper ores; and vanadium, chromium, molybdenum, and tungsten in steels. Detection limits, based on counting statistics obtained in count times of 10 to 100 sec, range from 0.03% for copper in ores to 0.2% for sulfur in coal. Both matrix absorption and enhancement effects were encountered and were eliminated or reduced substantially by suitable choice of source energy, by the use of nomograms, or by semiempirical correction factors based on attenuation or scattering coefficients.

Use Of A Solid-State Detector for the Analysis of X-Rays Excited in Silicate Rocks by Alpha-Particle Bombardment

1971 ◽  
Vol 15 ◽  
pp. 388-406 ◽  
Author(s):  
Ernest J. Franzgrote
Keyword(s):  
Alpha Particle ◽  
Particle Bombardment ◽  
Pulse Height ◽  
Silicon Detector ◽  
Alpha Particles ◽  
X Rays ◽  
Solid State Detector ◽  
X Ray ◽  
Alpha Scattering ◽  
Silicate Rocks

The analysis of alpha-excited X-rays has been studied as a possible addition to the alpha-scattering technique used on the Surveyor spacecraft for the first in situ chemical analyses of the lunar surface.Targets of pure elements, simple compounds, and silicate rocks have been exposed to alpha particles and other radiation from a curium-214 source and the resulting X-ray spectra measured by means of a cooled lithium-drifted silicon detector and pulse-height analysis.Alpha-particle bombardment is a simple and efficient means of X-ray excitation for light elements. Useful spectra of silicate rocks may be obtained in a few minutes with a source activity of 50 millicuries, a detector area of 0.1 cm2 and a sample distance of 3 cm. An advantage over electron excitation is the higher characteristic response relative to the bremsstrahlung continuum. Peak-to- background ratios of greater than 100 to 1 have been obtained for elemental targets. Relative efficiencies of X-ray excitation by alpha particles and by X-rays from the curium source have been determined.Resolution of the detector system used is approximately 150 eV for the lighter elements. This is sufficient to resolve the Kα X-rays of the geochemically important elements, Na, Mg, Al, and Si in silicate rocks. Although these and lighter elements are analyzed as well or better by the alpha-scattering and alpha-proton technique, the X-ray mode enables results to be obtained more quickly.The study shows that the addition of an X-ray mode to the alpha-scattering analysis technique would result in a significant improvement in analytical capability for the heavier elements. In particular, important indicators of geochemical differentiation such as K and Ca (which are only marginally separated in an alpha-scattering and alpha-proton analysis) may be determined quantitatively by measuring the alpha-excited X-rays. An X-ray detector is under consideration as an addition to an alpha-scattering instrument now under development for possible use on a Mars-lander mission.

Energy Dispersive Analysis for Adjacent Elements Using Two Single Channel Analyzers

1971 ◽  
Vol 15 ◽  
pp. 197-208
Author(s):  
Hubert K. Chow
Keyword(s):  
Single Channel ◽  
Matrix Effects ◽  
Pulse Height ◽  
Silicon Detector ◽  
Emission Spectra ◽  
Empirical Method ◽  
Energy Dispersive ◽  
Standard Samples ◽  
X Ray ◽  
Adjacent Element

Energy dispersive x-ray analysis has become an extremely useful analytical tool. The technique provides for the direct observation of x-ray emission spectra, eliminating the need for a dispersive crystal. The purpose of this reported investigation was to study the use of the technique with a simple pulse height analyzing system and to develop a routine method for correcting Interferences due to adjacent element spectral overlap and matrix effects.The analyzing system consists of a radioisotope source, a lithium drifted silicon detector, a preamplifier, an amplifier, two single channel analyzers and two digital ratemeters. In order to obtain results suitable for quantative measurement, a two-step empirical method was employed for the correction of peak overlapping and matrix effects. If two peaks in a spectrum overlap at their tails, one can set up a channel width of the analyzer to a region where there are no overlapping pulses. It is then possible to calibrate the ratio of the intensity obtained from this channel to that obtained from the whole peak in its pure state, i.e. without the appearance of a neighbor peak. The actual intensity of the peak in the overlapping spectrum is, therefore, the observed counts multiplied by the ratio. The next step is the correction of matrix effect by means of conventional empirical methods using standard samples. Two types of the samples, Zn-Cu powder mixtures and Ee-Cu in aqueous solutions, were studied to illustrate this method. The usefulness of applying the analyzing system and technique to industrial measurements, either on-line or batch, will also be discussed.

Going Nondispersive

1998 ◽  
Vol 4 (S2) ◽  
pp. 162-163
Author(s):  
Kurt F. J. Heinrich
Keyword(s):  
Electron Probe ◽  
Single Channel ◽  
Pulse Height ◽  
Silicon Detector ◽  
X Rays ◽  
X Ray ◽  
Energy Dispersion Spectrometer ◽  
Elementary Analysis ◽  
Geiger Muller Counter ◽  
Pulse Height Analysis

In February 1968 Ray Fitzgerald, Klaus Keil and myself published in Science a communication titled “Solid-State Energy-Dispersion Spectrometer for Electron Microprobe X-ray Analysis”. The authors describe the use of a lithium-drifted silicon detector for the direct identification of x-rays, without a diffracting crystal, in an electron probe. The subject of this paper was to modify profoundly the development of x-ray microanalysis in the years to follow.Pulse-height analysis of gamma rays detected in scintillation counters was widely used at the time. For radiation of energies below 30 keV, gas proportional counters were also employed. In elementary analysis by x-rays the poor energy resolution of these detectors limited the application of such a procedure, although single-channel pulse height analysis was employed as an adjunct to crystal spectrometers.In 1951, Raymond Castaing in his thesis described his invention of the electron probe microanalyzer, created by adding to a transmission electron microscope a curved-crystal spectrometer which focused the x-rays emitted by the specimen into a Geiger-Muller counter.

Erroneous Peaks in Energy Dispersive X-Ray Spectra

1975 ◽  
Vol 19 ◽  
pp. 161-165
Author(s):  
J. C. Russ
Keyword(s):  
Dead Time ◽  
Pulse Height ◽  
Energy Dispersive ◽  
Dead Time Correction ◽  
X Ray ◽  
Detector Geometry ◽  
Time Correction ◽  
Amplifier Design ◽  
Fluorescence Spectrometer ◽  
Selection Of

The necessary first step in using an x-ray fluorescence spectrometer for quantitative analysis is to obtain the intensities for the various elements. With a wavelength dispersive system this usually requires simply setting the crystal to the proper angle (and possibly adjusting the pulse height selector) and making a dead-time correction. With the energy dispersive x-ray fluorescence analyzer it is necessary to take into account the presence of erroneous peaks in the spectrum, to obtain true intensity values.False peaks due to diffraction of white tube radiation from the sample can usually be shifted to portions of the energy spectrum where they do not interfere with emission lines of interest by selection of the proper tube-sample-detector geometry. Modern amplifier design provides a built – in dead time correction and greatly reduces the effects of pulse-pile-up, although the latter phenomenon will still produce small peaks at exact multiples of major peaks.

Development of the Detector Response Function Approach for the Library Least-Squares Analysis of Energy-Dispersive X-Ray Fluorescence Spectra

1978 ◽  
Vol 22 ◽  
pp. 317-323 ◽  
Author(s):  
L. Wielopolski ◽  
R. P. Gardner
Keyword(s):  
Least Squares ◽  
Response Function ◽  
Fluorescence Spectra ◽  
Pulse Height ◽  
Energy Dispersive ◽  
Analytical Models ◽  
Detector Response ◽  
Height Distribution ◽  
Pulse Height Distribution ◽  
X Ray

A procedure to obtain analytical models for the elemental X-ray pulse-height distribution libraries necessary in the library least-squares analysis of energy-dispersive x-ray fluorescence spectra is outlined. This is accomplished by first obtaining the response function of Si(Li) detectors for incident photons in the energy range of interest. Subsequently this response function is used to generate the desired elemental library standards for use in the least-squares analysis of spectra, or it can be used directly within a least-squares computer program, thus eliminating the large amount of computer storage required for the standards.

Identification of origins of lesser snow geese by X-ray spectrometry

1977 ◽  
Vol 55 (4) ◽  
pp. 718-732 ◽  
Author(s):  
John P. Kelsall ◽  
Roland Burton
Keyword(s):  
Chemical Elements ◽  
Pulse Height ◽  
Silicon Detector ◽  
Discriminant Functions ◽  
Emission Energy ◽  
X Ray ◽  
Snow Geese ◽  
Lesser Snow Geese ◽  
Computer Controlled ◽  
The Times

An attempt to apply computer-controlled. X-ray spectrometric methods for the identification of origins of waterfowl, through the analysis of chemical elements in their primary flight feathers, is described. Materials were gathered from three geographically distinct populations of wild lesser snow geese (Chen caerulescens). They were laundered, dried, and irradiated by 25 mCi (1 Ci = 37 GBq) Americium 241. Chemical spectra were developed using a lithium-drifted silicon detector, and a computer-controlled pulse-height analyzer that provided results in 512 channels of emission energy between about 2.3 and 40 keV. Computer programs were written or adapted to process our data. Multivariate discriminant functions were used (among other techniques) to examine potential significant differences between populations, and between different year classes within one population. Attempts were made to classify unknown feathers through use of discriminant functions. Best results were obtained by measuring the areas under K alpha peaks of emission energy for recognizable chemical elements in the spectra and using those, and the times for analysis, as significant variables. Two other methods of using the data are compared with that method. Efforts to discriminate geographically different populations, and to classify unknowns are encouraging. However, there are residual problems to be dealt with.

Sign in / Sign up

Export Citation Format

Share Document