A Method of Liquid Analyses Providing Increased Sensitivity for Light Elements

1966 ◽  
Vol 10 ◽  
pp. 506-519
Author(s):  
D. W. Beard ◽  
E. M. Proctor
Keyword(s):  
Light Element ◽  
Sample Surface ◽  
X Rays ◽  
Light Elements ◽  
Element Analysis ◽  
X Ray ◽  
Surface Method ◽  
Liquid Cell ◽  
Increased Sensitivity ◽  
Typical Solution

AbstractA method for analyzing solutions using a sample surface directly exposed to the primary X-ray beam is discussed. This method eliminates the need for the conventional Mylar covered liquid cells. The advantages of this method are the elimination of the scattering of the longer wavelength X-rays and the absorption effects due to the Mylar covering, thereby giving significant improvement in peak-to-background ratios and peak intensities for the light elements. This increased sensitivity can be used to improve the limits of detectability for light elements in solutions, broaden the range of practical elemental determinations, and reduce the counting time for any light element analysis in liquids.A new liquid cell, developed for this technique, provides easily repeatable setting of target-to-sample distance and simplified preparation and handling of samples. A comparison between results obtained with conventional method and this uncovered sample surface method is made for typical solution applications.

Effect of X-ray Tube Window Thickness on Detection Limits for Light Elements in XRF Analysis

1994 ◽  
Vol 38 ◽  
pp. 299-305
Author(s):  
Daniel J. Whalen ◽  
D. Clark Turner
Keyword(s):  
Light Element ◽  
Detection Limits ◽  
X Rays ◽  
Light Elements ◽  
Absorption Data ◽  
Element Analysis ◽  
X Ray ◽  
Data Compilation ◽  
Beryllium Window ◽  
X Ray Background

Abstract Widespread interest in light element analysis using XRF has stimulated the development of thin x-ray tube windows. Thinner windows enhance the soft x-ray output of the tube, which more efficiently excite the light elements in the sample. A computer program that calculates the effect of window thickness on light element sample fluorescence has been developed. The code uses an NIST algorithm to calculate the x-ray tube spectrum given various tube parameters such as beryllium window thickness, operating voyage, anode composition, and take-off angle. The interaction of the tube radiation with the sample matrix is modelled to provide the primary and secondary fluorescence from the sample. For x-rays in the energy region 30 - 1000 eV the mass attenuation coefficients were interpolated from the photo absorption data compilation of Henke, et al. The code also calculates the x-ray background due to coherent and incoherent scatter from the sample, as well as the contribution of such scatter to the sample fluorescence. Given the sample fluorescence and background the effect of tube window thickness on detection limits for light elements can be predicted.

HIGH-RESOLUTION PIXE USING BRAGG’S SPECTROMETER

1991 ◽  
Vol 01 (03) ◽  
pp. 251-258 ◽  
Author(s):  
M. TERASAWA
Keyword(s):  
High Resolution ◽  
Heavy Ions ◽  
X Rays ◽  
Light Elements ◽  
Element Analysis ◽  
X Ray ◽  
Peak Intensity ◽  
Moderate Energy ◽  
Practical Analysis ◽  
Wavelength Selectivity

K, L, and M X-rays in the wavelengths between 6Å and 130Å generated by the bombardment of 200 keV protons and other heavy ions were measured by means of a wavelength dispersive Bragg’s spectrometer. The X-ray peak intensity was fairly high in general, while the background was very low. The technique was favorably applied to a practical analysis of several light elements (Be, B, C, N, O, and F). Use of moderate-energy heavy ions considering the wavelength selectivity in X-ray generation was effective for the element analysis. The high-resolution spectrometry in the analytical application of ion-induced X-ray generation was found to be useful for the study of fine electronic structure, e.g. satellite and hypersatellite X-ray study, and of the chemical state of materials.

Light Element Analysis

1969 ◽  
Vol 13 ◽  
pp. 26-48
Author(s):  
A. K. Baird
Keyword(s):  
Atomic Number ◽  
Matrix Effects ◽  
Light Element ◽  
Electron Excitation ◽  
Electron Gun ◽  
X Rays ◽  
Element Analysis ◽  
X Ray ◽  
High Emission ◽  
Quantitative Analyses

Qualitative and quantitative analyses of elements below atomic number 20, and extending to atomic number 4, have been made practical and reasonably routine only in the past five to ten years by advances in: 1) excitation sources; 2) dispersive spectrometers; 3) detection devices; and 4) reductions of optic path absorption. At present agreement is lacking on the best combination of parameters for light element analysis. The principal contrasts in opinion concern excitation.Direct electron excitation, particularly as employed in microprobe analysis (but not limited to such instruments), provides relatively high emission intensities of all soft X-rays, but also generates a high continuum, requires the sample to be at essentially electron gun vacuum, and introduces practical calibration problems (“matrix effects“). X-ray excitation of soft X-rays overcomes some of the latter three disadvantages, and has its own limitations. Sealed X-ray sources of conventional or semi-conventional design can provide useful (if not optimum) light element emission intensities down to atomic number 9, hut with serious loss of efficiency in many applications below atomic number 15 largely because of window-thinness limitations under electron bombardment.

Comparison of Experimental and Theoretical Intensities for a New X-Ray Tube for Light Element Analysis

1983 ◽  
Vol 27 ◽  
pp. 423-426 ◽  
Author(s):  
John Kikkert ◽  
Graham Hendry
Keyword(s):  
Atomic Number ◽  
Light Element ◽  
Fluorescence Spectrometry ◽  
Light Elements ◽  
Element Analysis ◽  
X Ray ◽  
Highly Sensitive ◽  
Low Sensitivity

While x-ray fluorescence spectrometry is a highly sensitive and highly repoducible method of analysing samples, its one weakness is its relatively low sensitivity for light elements. This is mainly due to two problems: firstly the low fluorescent yield of the low atomic number elements, and secondly to the inherent inefficiency of exciting these elements. While it is not possible to improve the fluorescent yield, considerable improvements in light element sensitivity can be achieved by improvements in x-ray tubes.

Light Element Analysis with TXRF

1991 ◽  
Vol 35 (B) ◽  
pp. 947-952
Author(s):  
Christina Streli ◽  
Peter Wobrauschek ◽  
Hannes Aiginger
Keyword(s):  
Trace Element Analysis ◽  
Light Element ◽  
Fluorescence Analysis ◽  
Analytical Tool ◽  
Total Reflection ◽  
Light Elements ◽  
Element Analysis ◽  
X Ray ◽  
Background Reduction ◽  
Powerful Analytical Tool

AbstractTotal Reflection X-Ray Fluorescence Analysis (TXRF) has become a powerful analytical tool for trace element analysis. Because of its advantages in excitation and background reduction TXRF has been applied for the analysis of light elements (C,O,F,Na,...). A special Ge(HP) detector offering an ultra thin window in combination with a spectrometer specially designed for the requirements of light element analysis was used. Also a new windowless X-ray tube for efficient excitation of the light elements was tested. The system was checked with standard aqueous solutions; detection limits in the ng range (7 ng for O) are obtained.

A REVIEW OF PARTICLE-INDUCED X-RAY EMISSION IN GEOLOGY

1991 ◽  
Vol 01 (04) ◽  
pp. 311-338 ◽  
Author(s):  
J. D. MACARTHUR ◽  
XIN-PEI MA
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Light Element ◽  
X Rays ◽  
Geological Samples ◽  
Geological Material ◽  
Element Analysis ◽  
X Ray ◽  
Gamma Ray Emission

Particle-induced X-ray emission is very well suited for the analysis of geological samples. This review discusses the characteristics for such analyses. For light-element analysis, the complimentary technique of particle-induced gamma ray emission is also discussed since the emission of gamma rays occurs simultaneously with the X-rays. Not only are exploratory investigations of PIXE's capabilities presented but also synopses of studies aimed at answering geological questions. The latter have become more and more common in the last few years, an indication of PIXE's maturity as a technique for clement analysis of geological material.

Element Analysis of Microarea with Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 438-439
Author(s):  
Yasushi Kokubo ◽  
Hirotami Koike ◽  
Teruo Someya
Keyword(s):  
Electron Microscope ◽  
Auger Spectroscopy ◽  
Electron Gun ◽  
X Rays ◽  
Light Elements ◽  
Thermal Electron ◽  
Element Analysis ◽  
Solid State Detector ◽  
X Ray ◽  
State Detector

In recent years, X-ray elemental analysis of specimen microareas has been widely carried out, using an electron microscope fitted with a solid state detector, i.e., an energy dispersive type spectrometer. With this method, it is very difficult to detect light elements, especially those present in thin specimens used for electron microscopy, because the X-ray yield for light elements is extremely small. And in the microarea range of 1000 Å or less, it is very difficult to obtain accurate values, owing to the diffusion of X-rays in the specimen. Although element analysis by Auger spectroscopy is reportedly promising for light elements, this method requires large probe currents of the order of 10−8 A or more. Thus, so long as an ordinary thermal electron cathode is used, this method allows analysis of only microareas measuring lp or more, due to the low brightness of the electron gun.

Determination of the detection efficiency of an UTW detector and modelling of spectra used for the quantification of EDS analyses of light elements

1992 ◽  
Vol 50 (2) ◽  
pp. 1234-1235
Author(s):  
Pierre Hovington ◽  
Gilles L'Espéiance
Keyword(s):  
Data Processing ◽  
Detection Efficiency ◽  
Light Element ◽  
X Rays ◽  
Routine Laboratory ◽  
Light Elements ◽  
Characteristic Peak ◽  
Laboratory Procedure ◽  
X Ray

The increased use of Si(Li) energy dispersive x-ray spectrometers (EDS) with a windowless (WL) or ultra thinwindow (UTW) detectors has made the detection of light elements down to Be a routine laboratory procedure. The quantification of EDS spectra implies that the net intensity of the characteristic peak of interest must be determined accurately. For light-element x-rays for which the background is non linear and for which the Kα lines can often overlap with the L and M lines of transition metals, the simple determination of the characteristic intensity is not a straightforward operation and often requires sophisticated data processing. The use of a conventional least-squares fitting technique with prefiltering of standard spectra for deconvolution is made difficult by the non-linearity of the background, the presence of the triggered noise peak below 0.3 KeV, and the lack of appropiate standards. In addition to the difficulty associated with the determination of the net intensity, the uncertainties for the detection efficiency below 1 Kev has limited the use of standardless procedures for quantification.

Light Element Analysis with an Electron Microprobe

1964 ◽  
Vol 8 ◽  
pp. 341-351 ◽  
Author(s):  
Poen Sing Ong
Keyword(s):  
Electron Microprobe ◽  
Analytical Data ◽  
Light Element ◽  
Spectrochemical Analysis ◽  
Light Elements ◽  
Instrumental Performance ◽  
Element Analysis ◽  
X Ray ◽  
Lead Stearate

AbstractIn the microprobe, lead stearate decanoate multilayer analyzers have proven to be practical components for X-ray spectrochemical analysis of the light elements. Better controlled techniques in the deposition of the layers have already produced analyzers yielding improved peak to background ratios as well as higher counting rates. Operational techniques, optimizing instrumental performance, will be discussed. Analytical data on the elements fluorine through boron, obtained with a modified commercial microprobe, will be presented.

50 Years of EPMA / Today’s and Tomorrow’s Instruments.

1999 ◽  
Vol 5 (S2) ◽  
pp. 554-555
Author(s):  
C. Conty
Keyword(s):  
Light Element ◽  
Electron Optics ◽  
X Rays ◽  
Element Analysis ◽  
X Ray ◽  
Quantitative Microanalysis ◽  
Drawing Board ◽  
The University ◽  
Ray Path ◽  
Non Destructive

The Sepia years. 1951. Castaing’s thesis(1) : Genesis of a Non-Destructive and truly Quantitative Microanalysis method. 1958. The beginning of commercial microprobes : Early instruments had no computers and were lacking special analyzing crystals, but overall they were well designed. Modern features we are familiar with today, such as light element analysis, field emission gun, Energy Dispersive analysis, analysis of insulated material and scanning analysis, although not widely implemented, were discussed in scientific reviews even then(2) 1963. One of my early personal experience: The daring job of obtaining Castaing’s acceptance for his Cameca-buih EPMA at the University of Paris/Orsay.From early models to present microprobes Early microprobes were developed, after WWII, in a world driven by metallurgy. They had few WD spectrometers, usually at low take off angle. However, the need for light element analysis and the fast growing use of EPMA in geology have sent the manufacturers back to the drawing board. Why ? The design of modern microprobes was a compromise between light optics, electron optics and higher take off angle X-ray spectrometry. There were three possible designs of X-ray path geometry : X-rays through the(final) lens, X-rays through the gap of the lens, X-rays outside the lens, hence three suppliers arose based on these concepts.Present and future EPMA improvements. As in the initial era of EPMA newer applications will point the direction in which the electron microprobe of the future should evolve.

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