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.

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.

X-ray detection performance of a 300KV field-emission Analytical Electron Microscope

1993 ◽  
Vol 51 ◽  
pp. 250-251
Author(s):  
C. E. Lyman ◽  
J. I. Goldstein ◽  
D.B. Williams ◽  
D.W. Ackland ◽  
S. von Harrach ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Detection Performance ◽  
Electron Gun ◽  
X Rays ◽  
X Ray ◽  
Analytical Electron ◽  
Analytical Electron Microscope

A major goal of analytical electron micrsocopy (AEM) is to detect small amounts of an element in a given matrix at high spatial resolution. While there is a tradeoff between low detection limit and high spatial resolution, a field emission electron gun allows detection of small amounts of an element at sub-lOnm spatial resolution. The minimum mass fraction of one element measured in another is proportional to [(P/B)·P]-1/2 where the peak-to-background ratio P/B and the peak intensity P both must be high to detect the smallest amount of an element. Thus, the x-ray detection performance of an analytical electron microscope may be characterized in terms of standardized measurements of peak-to-background, x-ray intensity, the level of spurious x-rays (hole count), and x-ray detector performance in terms of energy resolution and peak shape.This paper provides measurements of these parameters from Lehigh’s VG Microscopes HB-603 field emission AEM. This AEM was designed to provide the best x-ray detection possible.

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.

Material analysis end-station of the Hyogo-ken beamline at SPring-8

1998 ◽  
Vol 5 (3) ◽  
pp. 509-511 ◽  
Author(s):  
T. Kaneyoshi ◽  
T. Ishihara ◽  
H. Yoshioka ◽  
M. Motoyama ◽  
S. Fukushima ◽  
...  
Keyword(s):  
Surface Analysis ◽  
Three Dimensional ◽  
Grazing Incidence ◽  
Incidence Geometry ◽  
X Rays ◽  
X Ray Diffraction ◽  
Solid State Detector ◽  
X Ray ◽  
Grazing Incidence Geometry ◽  
State Detector

Plans to construct surface-analysis equipment which will be placed on beamline BL24XU of SPring-8 are presented. There are three experimental hutches in BL24XU, which are available simultaneously by using diamond monochromators as beam splitters. The purpose of the surface-analysis equipment is the simultaneous measurement of fluorescent and diffracted X-rays in grazing-incidence geometry. The instrument is equipped with a solid-state detector (SSD) and a flat position-sensitive proportional counter (PSPC) combined with analysing crystals for X-ray fluorescence (XRF) analysis. A curved PSPC and the goniometer that mounts the SSD used for XRF are also installed for X-ray diffraction. X-ray fluorescence holography and polarized X-ray emission spectroscopy modes are available, so three-dimensional images of atomic configurations and also the anisotropic structure of materials will be studied.

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.

Comparison Of A Mosaic-Crystal Spectrometer To Ahigh-Performance Solid-State Detector For X-Ray Microfluorescence Analysis

1998 ◽  
Vol 524 ◽  
Author(s):  
J.-S. Chung ◽  
S. Isa ◽  
C. J. Sparks ◽  
G. E. Ice ◽  
S. Mchugo ◽  
...  
Keyword(s):  
Solid State ◽  
Trace Element Analysis ◽  
Crystal Spectrometer ◽  
Element Analysis ◽  
Solid State Detector ◽  
X Ray ◽  
Detectable Limit ◽  
Minimum Detectable Limit ◽  
Mosaic Crystal ◽  
State Detector

ABSTRACTThe minimum-detectable-limit of a compact double-focusing graphite mosaic-crystal spectrometer is compared to the minimum-detectable-limit from a high-performance Ge solidstate detector. The solid angle and efficiency of the solid-state detector is much greater than for the crystal spectrometer. However, the better signal-to-noise of the spectrometer and its insensitivity to matrix fluorescence and scattering can give it a better minimum-detectable-limit for trace element analysis. The relative advantages of the two detectors are illustrated for some simple test samples. The performance of the crystal spectrometer compared to the solid-state detector increases as the flux in the x-ray probe increases. This makes crystal spectrometers especially interesting for use with new high intensity 3rd generation synchrotron microprobes. An estimate is made of the source and sample conditions favored for each detector.

New transmission-type X-ray filters consisting of amorphous multilayer films

1998 ◽  
Vol 5 (3) ◽  
pp. 603-605
Author(s):  
Yasuo Takagi ◽  
Muneyuki Imafuku
Keyword(s):  
Multilayer Films ◽  
X Rays ◽  
Solid State Detector ◽  
Sputtering Deposition ◽  
X Ray ◽  
Dependent Absorption ◽  
Diffraction Peaks ◽  
Sputter Deposited ◽  
Fluorescence Xafs ◽  
State Detector

New transmission-type X-ray filters have been developed. The filters consist of X-ray-amorphous metal (less than 30 Å)/metalloid (∼10 Å) multilayer films sputter-deposited on X-ray-transparent polymer substrates. Such metal/metalloid multilayer films show only very broad diffraction peaks, since the metal and metalloid layers forming the multilayer films are usually X-ray amorphous if the layers are sufficiently thin. The filters use the wavelength-dependent absorption phenomena near absorption edges of elements to reduce the intensity of transmitted X-rays, without generating any crystalline sharp peaks which cause serious problems in experiments such as fluorescence XAFS measurements. The multilayer-film filters were prepared by a multi-target magnetron sputtering deposition technique, paying special attention to the homogeneity of the layer thickness by spinning substrates of the films. The filters are useful in reducing the intensity of undesirable fluorescence emissions and improving the signal-to-background ratios of data acquired in various measurements using a solid-state detector.

An X-Ray Detector Using a Fluorescent Material ZnS:Ag Attached on a Phototransistor in Darlington Configuration

2015 ◽  
Vol 771 ◽  
pp. 21-24
Author(s):  
Kusminarto ◽  
Ramacos Fadela
Keyword(s):  
Ct Scan ◽  
Linear Correlation ◽  
Imaging System ◽  
Active Area ◽  
Effective Diameter ◽  
X Rays ◽  
Solid State Detector ◽  
X Ray ◽  
Detector Output ◽  
State Detector

X-rays have been widely used in medical imaging system. CT Scan is one of the important diagnostic equipments in medical field that uses X-rays as a probe. In the latest CT-Scan generation an array of X-ray detector in a gantry is employed. Solid state detector and gas filled detector are currently used. These type of detector have relatively large in physical size. This influenses the size of the machine as well as its performance. In order to obtain an X-ray detector in a small size a phototransistor was exploited. The phototransistor was attached on a fluoroscent screen and arranged in Darlington configuration. The phototransistor in Darlington configuration was calibrated using visible light. The results showed that there was a linear correlation between the phototransistor output (mV) and the light intensity impinging on the phototransistor surface. A fluoroscent material (ZnS:Ag) then attached on the phototransistor surface. They work as an X-ray detector and calibrated using an X-ray beam generated from an X-ray machine. The results also confirmed that there was a linear correlation between the detector output (mV) and the X-ray intensity stricking the detector surface. The active area of the detector was explored by scanning the surface of the detector in vertical as well as in horizontal directions. The effective diameter of the active area of the detector was found to be 2.2 mm.

Glancing Angle X-ray Absorption Spectroscopy

1990 ◽  
Vol 34 ◽  
pp. 13-22 ◽  
Author(s):  
G. N. Greaves
Keyword(s):  
Absorption Spectroscopy ◽  
X Rays ◽  
Solid State Detector ◽  
X Ray ◽  
Operational Conditions ◽  
Surfaces And Interfaces ◽  
Glancing Angle ◽  
X Ray Absorption ◽  
State Detector ◽  
Monolayer Coverage

AbstractThe use of glancing angles of incidence enables X-ray Absorption Spectroscopy to be measured as a function of depth from the surface of a material into the bulk. As x-rays rather than photoelectrons are detected, a UHV environment is not required and instead surfaces and interfaces can be examined under realistic operational conditions. Whilst the reflected beam carries the fine structure of concentrated species in the imaginary part of the refractive index, this is obscured by the contribution from the real part for angles greater than ϕc, the critical angle for total external reflection. Measuring the x-ray fluorescence offers more flexibility, particularly for dilute systems. The use of synchrotron radiation in conjunction with a multi-element Solid State Detector enables impurity loadings down to a few 1019 cm-3 to be measured which for ion implants is equivalent to around half-monolayer coverage at the surface. This sensitivity makes it practical to examine impurities in semiconductors at realistic dopant levels.

Sign in / Sign up

Export Citation Format

Share Document