Computer programs for the calculation of x-ray intensities emitted by elements in multi-layer structures

1990 ◽  
Vol 48 (2) ◽  
pp. 216-217
Author(s):  
G.F. Bastin ◽  
H.J.M. Heijligers ◽  
J.M. Dijkstra
Keyword(s):  
Software Package ◽  
Light Element ◽  
Matrix Correction ◽  
Excellent Performance ◽  
Element Analysis ◽  
X Ray ◽  
Know How ◽  
Accurate Knowledge ◽  
Layer Structures ◽  
Bulk Matrix

For the calculation of X-ray intensities emitted by elements present in multi-layer systems it is vital to have an accurate knowledge of the x-ray ionization vs. mass-depth (ϕ(ρz)) curves as a function of accelerating voltage and atomic number of films and substrate. Once this knowledge is available the way is open to the analysis of thin films in which both the thicknesses as well as the compositions can usually be determined simultaneously.Our bulk matrix correction “PROZA” with its proven excellent performance for a wide variety of applications (e.g., ultra-light element analysis, extremes in accelerating voltage) has been used as the basis for the development of the software package discussed here. The PROZA program is based on our own modifications of the surface-centred Gaussian ϕ(ρz) model, originally introduced by Packwood and Brown. For its extension towards thin film applications it is required to know how the 4 Gaussian parameters α, β, γ and ϕ(o) for each element in each of the films are affected by the film thickness and the presence of other layers and the substrate.

Vacuum X-Ray Instrumentation and its Application to Mill-Products Control

1961 ◽  
Vol 5 ◽  
pp. 477-485
Author(s):  
H. T. Dryer ◽  
E. Davidson ◽  
G. Andermann
Keyword(s):  
Sample Preparation ◽  
Light Element ◽  
Analytical Sensitivity ◽  
Element Analysis ◽  
X Ray ◽  
Design Concepts ◽  
Precision And Accuracy ◽  
The Way

AbstractWith the introduction in 1960 of the first commercial multichannel vacuum X-ray spectrometers, ARL opened the way for greater economy of operation for light-element analysis over conventional helium-path instrumentation. The design concepts and features of these instruments are discussed, including the adaptability to “on-stream” or continuous analyzer programs. The successful application of vacuum X-ray equipment for the analysis of ores, concentrates, and slags will be presented. Factors relating to sample preparation, precision, and accuracy are given and analytical sensitivity and speed are covered.

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.

Improved micro x-ray fluorescence spectrometer for light element analysis

2010 ◽  
Vol 81 (5) ◽  
pp. 053707 ◽  
Author(s):  
Stephan Smolek ◽  
Christina Streli ◽  
Norbert Zoeger ◽  
Peter Wobrauschek
Keyword(s):  
Light Element ◽  
Element Analysis ◽  
X Ray ◽  
Fluorescence Spectrometer

New Technologies for Microanalysis and Element Imaging in THJ Scanning Electron Microscope

2001 ◽  
Vol 7 (S2) ◽  
pp. 884-885
Author(s):  
Paul Smith ◽  
John Gannon ◽  
Frank Eggert
Keyword(s):  
Electron Microscopy ◽  
Energy Resolution ◽  
New Technologies ◽  
New Technology ◽  
Operating Cost ◽  
Light Element ◽  
Sem Images ◽  
High Count ◽  
Element Analysis ◽  
X Ray

RÖNTEC’s UHV Dewar detectors have established new standards for high resolution, lowmaintenance, low operating cost, and reliability in Si(Li) X-ray detectors. Now, the recently introduced XFlash® series X-ray detectors are enabling new methodologies for microanalysis and element imaging in the SEM. These detectors are compact, liquid-nitrogen-free semiconductor Xray detectors that are based on Silicon Drift Diode (SDD) technology. XFlash detectors produce extraordinarily high count rates with excellent energy resolution and have introduced ultra-fast microanalysis and element mapping to the SEM world. The addition of color to SEM images enables easy visualization of element distributions and allows the microstructural features and compositional variations of different materials to be more readily identified. Persons unfamiliar with electron microscopy can more readily interpret color images than black and white or gray scale images. This new technology has great potential to revolutionize electron microscopy.RÖNTEC’s UHV Dewar Detector offers the highest long-term stability and best energy resolution ever specified for a commercial Si(Li) detector (less than 129 eV). The UHV design leads to small size and weight (for reduced column loading) along with extremely low nitrogen consumption and low susceptibility to microphonics. The UHV detector never ices up and thus never requires defrosting or warm-ups. It is available with a variety of entrance windows for light element analysis.

Developments in Scanning Auger Microscopy

1978 ◽  
Vol 36 (3) ◽  
pp. 280-291
Author(s):  
J.A. Venables ◽  
A.P. Janssen
Keyword(s):  
Auger Electron ◽  
Light Element ◽  
Mean Free Path ◽  
Element Analysis ◽  
Auger Electrons ◽  
X Ray ◽  
Atomic Relaxation ◽  
Auger Microscopy ◽  
Energy Processes ◽  
Inelastic Mean Free Path

In the last decade, Auger Electron Spectroscopy (AES) has become a standard tool of surface physics and chemistry. Under electron bombardment, atoms emit Auger electrons having characteristic energies, so that the atomic species present can be identified after the manner of X-ray spectroscopy. AES is complementary to X-ray spectroscopy in several ways. First, it is much more surface sensitive, since the inelastic mean free path for Auger electrons, whose energies are typically in the range 50 - 1500 eV, is ~ lnm. Second, atomic relaxation following the primary ionization results in either an X-ray or an Auger electron. Auger emission is dominant for low energy processes, so that AES is relatively more favourable for light element analysis than X-ray spectroscopy.

Quantitative light-element analysis using parallel EELS

1991 ◽  
Vol 49 ◽  
pp. 722-723
Author(s):  
J. A. Hunt ◽  
A. J. Strutt ◽  
D. B. Williams
Keyword(s):  
Light Element ◽  
Single Scattering ◽  
Fluorescence Yield ◽  
Emission Spectrometry ◽  
Quality Of Data ◽  
Element Analysis ◽  
X Ray ◽  
Electron Energy Loss Spectrometry ◽  
Electron Energy Loss

Electron energy-loss spectrometry (EELS) is theoretically superior to x-ray emission spectrometry (XES) for light element microanalysis. The x-ray fluorescence yield decreases proportional to Z4, thus dramatically reducing characteristic x-ray production. However, the ionization cross section increases and so EELS becomes more efficient as Z decreases. Despite these advantages light element microanalysis using XES is often preferred to EELS. There are two major reasons why EELS is not more widespread. First, very thin specimens are needed to minimize plural scattering so quantification can proceed assuming single scattering. Secondly, many experimental variables make EELS difficult, particularly for microanalysts accustomed to the x-ray 'turn-key' approach to quantification. The former problem is being overcome with multiple least-squares (MLS) fitting deconvolution routines, while the latter has largely been solved by the development of parallel EELS (PEELS) and powerful analysis software. In this paper we show the quality of data currently available using PEELS.

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.

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.

Windowless X‐Ray Tube Spectrometer for Light Element Analysis

1964 ◽  
Vol 35 (3) ◽  
pp. 381-383 ◽  
Author(s):  
Ralph W. G. Wyckoff ◽  
Franklin D. Davidson
Keyword(s):  
Light Element ◽  
Element Analysis ◽  
X Ray
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