Light-element analysis with electrons and x-rays in a high-resolution STEM

1985 ◽  
Vol 18 (1-4) ◽  
pp. 173-184 ◽  
Author(s):  
L.E. Thomas
Keyword(s):  
High Resolution ◽  
Light Element ◽  
X Rays ◽  
Element Analysis

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.

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.

Sensitivity in light element analysis by 2 MeV and 150 keV proton and photon induced X-rays

1978 ◽  
Vol 150 (3) ◽  
pp. 523-528 ◽  
Author(s):  
Yoshiko Moriya ◽  
Yasuro Ato ◽  
Sohji Miyagawa
Keyword(s):  
Light Element ◽  
X Rays ◽  
Element Analysis

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.

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.

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.

Low Voltage Biological X-Ray Microanalysis: Progress and a Remaining Problem

2000 ◽  
Vol 6 (S2) ◽  
pp. 758-759
Author(s):  
Patrick Echlin
Keyword(s):  
Low Voltage ◽  
Light Element ◽  
Primary Electron ◽  
X Rays ◽  
Element Analysis ◽  
X Ray ◽  
Analytical Technique ◽  
The Past ◽  
Beam Sample ◽  
Wide Range

Experimental work in a number of research groups over the past five years have demonstrated, unequivocally, that low voltage i.e. 5kV and below, quantitative x-ray microanalysis is a valid analytical technique which can be applied to a wide range of specimens. The advantages of this approach are now generally well known and include improved image contrast, diminished bulk charging of the sample and for bulk specimens, a reduction in the size of the beam-sample interactive volume from which the x-rays are generated, and as a consequence, a considerable improvement in the microanalytical spatial resolution. In addition, low voltages ensure a sensitive surface analysis procedure which provides true topographic contrast and that in the case of light element analysis, quantitation is simplified because the atomic number (Z), absorption (A) and fluorescence (F) effects are minimised. All these advantages are improved further if one uses a field emission gun as the primary electron source.

Evaluation of Soft and Hard Scarttered X-Rays as an Internal Standard for Light Element Analysis

1969 ◽  
Vol 13 ◽  
pp. 80-93
Author(s):  
David L. Taylor ◽  
George Andermann
Keyword(s):  
Matrix Effects ◽  
Wave Length ◽  
Internal Standard ◽  
Light Element ◽  
X Rays ◽  
Element Analysis ◽  
Scattering Angle ◽  
Wide Range ◽  
The Matrix ◽  
Internal Standardization

In the research described, the use of scattered x-rays has been successfully applied as an internal standard for the analysis of calcium in aqueous specimens containing a wide range of matrix components. In addition to the demonstration of the utility of scattered x-rays for light element analysis, some comments are offered on the fundamental aspects of this technique, since to date the method has not been explained thoroughly. The present research represents a continued effort to determine the fundamental importance of various parameters intrinsic to any collection of atoms undergoing scattering, such as the Rayleigh-Compton ratio, the scattering angle, the wave length utilized, and the presence or absence of discontinuities in the matrix absorption coefficient. It has been concluded that large values of the scattering angle coupled with short wavelength tend to yield improved internal compensation. The results also indicate that for light matrices the Compton component of the scattered continuum is of particular importance in achieving good internal standardization for matrix effects.

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