SEM-XRF

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SEM/EDS spectra is compared to SEM-XRF spectra for a NIST 610 standard. SEM-XRF example.jpg
SEM/EDS spectra is compared to SEM-XRF spectra for a NIST 610 standard.

SEM-XRF is an established technical term for adding a (typically micro-focus) X-ray generator (X-ray source) to a Scanning Electron Microscope (SEM). Technological progress in the fields of small-spot low-power X-ray tubes and of polycapillary X-ray optics has enabled the development of compact micro-focus X-ray sources that can be attached to a SEM equipped for energy-dispersive X-ray spectroscopy (EDS, EDX, EDXS or XEDS). [1]

Contents

As shown in the image at right, when micro-focus X-ray fluorescence (microXRF) is performed with a SEM, elemental analysis analytical figures of merit are extended to the point where trace level quantification and bulk analysis are possible. [2] By combining the analytical information obtained from the X-ray spectra excited with electrons and with photons respectively, the main elements as well as trace elements, of low and high atomic number, can be analyzed – albeit with different spatial resolutions. [3]

In 1986, Sandia and Lawrence Livermore National Labs coauthored a paper (with Kevex Corporation) regarding parameters affecting X-ray micro-fluorescence. [4] As a followup in 1988, Cross & Wherry described an X-ray micro-fluorescence analyzer which combines the nondestructive analytical method of X-ray fluorescence with relatively small spatial discrimination (less than 50 μm) such that composition (chemistry), thickness and micro-structural measurements can be made on a wide variety of heterogeneous materials in a few seconds. It was shown that, by scanning samples with an X-Y stage, quantitative or qualitative micro-structural information could be gathered. [5] Both these papers provided a preview into the coming integration of Micro-X-ray fluorescence with SEM.

By 1991, Pozsgai published a review article detailing the possibilities of carrying out x-ray micro-fluorescence analysis within the SEM context. The main approaches involved converting the electron optical column of an electron microscope into a transmission x-ray tube, using micro-focusing x-ray tubes, combining x-ray tubes with capillary techniques, as well as combining x-ray tubes with monochromators and applying synchrotron radiation. [6]

SEM-XRF was first commercialized by IXRF Systems (Austin, TX) in March 2005. [7] Bruker Corporation (Billerica, MA) followed in August 2013. [8]

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<span class="mw-page-title-main">Analytical chemistry</span> Study of the separation, identification, and quantification of the chemical components of materials

Analytical chemistry studies and uses instruments and methods to separate, identify, and quantify matter. In practice, separation, identification or quantification may constitute the entire analysis or be combined with another method. Separation isolates analytes. Qualitative analysis identifies analytes, while quantitative analysis determines the numerical amount or concentration.

<span class="mw-page-title-main">Microscopy</span> Viewing of objects which are too small to be seen with the naked eye

Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye. There are three well-known branches of microscopy: optical, electron, and scanning probe microscopy, along with the emerging field of X-ray microscopy.

<span class="mw-page-title-main">Scanning electron microscope</span> Type of electron microscope

A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that contain information about the surface topography and composition of the sample. The electron beam is scanned in a raster scan pattern, and the position of the beam is combined with the intensity of the detected signal to produce an image. In the most common SEM mode, secondary electrons emitted by atoms excited by the electron beam are detected using a secondary electron detector. The number of secondary electrons that can be detected, and thus the signal intensity, depends, among other things, on specimen topography. Some SEMs can achieve resolutions better than 1 nanometer.

<span class="mw-page-title-main">X-ray fluorescence</span> Emission of secondary X-rays from a material excited by high-energy X-rays

X-ray fluorescence (XRF) is the emission of characteristic "secondary" X-rays from a material that has been excited by being bombarded with high-energy X-rays or gamma rays. The phenomenon is widely used for elemental analysis and chemical analysis, particularly in the investigation of metals, glass, ceramics and building materials, and for research in geochemistry, forensic science, archaeology and art objects such as paintings.

Gold fingerprinting is a method of identifying an item made of gold based on the impurities or trace elements it contains.

<span class="mw-page-title-main">Energy-dispersive X-ray spectroscopy</span> Analytical technique used for the elemental analysis or chemical characterization of a sample

Energy-dispersive X-ray spectroscopy, sometimes called energy dispersive X-ray analysis or energy dispersive X-ray microanalysis (EDXMA), is an analytical technique used for the elemental analysis or chemical characterization of a sample. It relies on an interaction of some source of X-ray excitation and a sample. Its characterization capabilities are due in large part to the fundamental principle that each element has a unique atomic structure allowing a unique set of peaks on its electromagnetic emission spectrum. The peak positions are predicted by the Moseley's law with accuracy much better than experimental resolution of a typical EDX instrument.

<span class="mw-page-title-main">X-ray spectroscopy</span> Technique to characterize materials using X-ray radiation

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A microprobe is an instrument that applies a stable and well-focused beam of charged particles to a sample.

<span class="mw-page-title-main">Electron microprobe</span> Instrument for the micro-chemical analysis of solids

An electron microprobe (EMP), also known as an electron probe microanalyzer (EPMA) or electron micro probe analyzer (EMPA), is an analytical tool used to non-destructively determine the chemical composition of small volumes of solid materials. It works similarly to a scanning electron microscope: the sample is bombarded with an electron beam, emitting x-rays at wavelengths characteristic to the elements being analyzed. This enables the abundances of elements present within small sample volumes to be determined, when a conventional accelerating voltage of 15-20 kV is used. The concentrations of elements from lithium to plutonium may be measured at levels as low as 100 parts per million (ppm), material dependent, although with care, levels below 10 ppm are possible. The ability to quantify lithium by EPMA became a reality in 2008.

<span class="mw-page-title-main">Scanning transmission electron microscopy</span> Instrument that produces images by scanning electrons across a sample

A scanning transmission electron microscope (STEM) is a type of transmission electron microscope (TEM). Pronunciation is [stɛm] or [ɛsti:i:ɛm]. As with a conventional transmission electron microscope (CTEM), images are formed by electrons passing through a sufficiently thin specimen. However, unlike CTEM, in STEM the electron beam is focused to a fine spot which is then scanned over the sample in a raster illumination system constructed so that the sample is illuminated at each point with the beam parallel to the optical axis. The rastering of the beam across the sample makes STEM suitable for analytical techniques such as Z-contrast annular dark-field imaging, and spectroscopic mapping by energy dispersive X-ray (EDX) spectroscopy, or electron energy loss spectroscopy (EELS). These signals can be obtained simultaneously, allowing direct correlation of images and spectroscopic data.

<span class="mw-page-title-main">Gunshot residue</span> Particles expelled from the muzzle of a gun

Gunshot residue (GSR), also known as cartridge discharge residue (CDR), gunfire residue (GFR), or firearm discharge residue (FDR), consists of all of the particles that are expelled from the muzzle of a gun following the discharge of a bullet. It is principally composed of burnt and unburnt particles from the explosive primer, the propellant (gunpowder), and vaporized lead. The act of firing a bullet incites a very violent explosive reaction that is contained within the barrel of the gun, which can cause the bullet, the barrel, or the cartridge to become chipped. Meaning gunshot residue may also included metal fragments from the cartridge casing, the bullets jacket, as well as any other dirt or residue contained within the barrel that could have become dislodged.

<span class="mw-page-title-main">Focused ion beam</span> Device

Focused ion beam, also known as FIB, is a technique used particularly in the semiconductor industry, materials science and increasingly in the biological field for site-specific analysis, deposition, and ablation of materials. A FIB setup is a scientific instrument that resembles a scanning electron microscope (SEM). However, while the SEM uses a focused beam of electrons to image the sample in the chamber, a FIB setup uses a focused beam of ions instead. FIB can also be incorporated in a system with both electron and ion beam columns, allowing the same feature to be investigated using either of the beams. FIB should not be confused with using a beam of focused ions for direct write lithography. These are generally quite different systems where the material is modified by other mechanisms.

Ceramic petrography is a laboratory-based scientific archaeological technique that examines the mineralogical and microstructural composition of ceramics and other inorganic materials under the polarised light microscope in order to interpret aspects of the provenance and technology of artefacts.

Semiconductor characterization techniques are used to characterize a semiconductor material or device. Some examples of semiconductor properties that could be characterized include the depletion width, carrier concentration, carrier generation and recombination rates, carrier lifetimes, defect concentration, and trap states.

TESCAN is one of the world's leading manufacturers[1] of Scanning Electron Microscopes (SEM), Focused Ion Beam-Scanning Electron Microscopes (FIB-SEM), Scanning Transmission Electron Microscopes (STEM), and microcomputed tomography (microCT).[2] TESCAN serves customers in materials science, geosciences, life sciences and semiconductor markets. TESCAN is located in Brno, which is considered to be the cradle of electron microscopy in Europe.[3] TESCAN has now produced over 3,000 SEMs and FIB-SEMs [4].

The Rathgen Research Laboratory is a Research Institute of the Berlin State Museums under the auspices of the Prussian Cultural Heritage Foundation. It carries out cross-material conservation science, art technology and archaeometry studies of fine arts and cultural artifacts to determine composition, age and authenticity and provide advice on their restoration. It further conducts academic research on scientific issues concerning the care and preservation of monuments and archaeological sites. Founded in 1888 as the Chemical Laboratory of the Royal Museums in Berlin, it is the oldest museum laboratory in world and bears the name of its first director, Dr. Friedrich Rathgen.

<span class="mw-page-title-main">Solaris (synchrotron)</span>

SOLARIS is the only synchrotron in Central-Eastern Europe. Built in Poland in 2015, under the auspices of the Jagiellonian University, it is located on the Campus of the 600th Anniversary of the Jagiellonian University Revival, in the southern part of Krakow. It is the central facility of the National Synchrotron Radiation Centre SOLARIS.

<span class="mw-page-title-main">Raimond Castaing</span>

Raimond Bernard René Castaing, also spelt as Raymond Castaing, was a French solid state physicist and inventor of various materials characterization methods. He was the founder of the French school of microanalysis and is referred to as the father of microanalysis.

References

  1. Integrated Electron and X-Ray Induced Microbeam XRF in the SEM. Cross BJ, Witherspoon KC. Microscopy Today. Jul;12(4):20-3 (2004).
  2. Micro-Focus X-Ray Fluorescence (µ-XRF) as an Extension of the Analytical SEM.. V.-D. Hodoroaba, et al. Microscopy and Microanalysis. 16(S2):904-905, August 2010.
  3. [Hodoroaba, V., Rackwitz, V., & Reuter, D. (2010). Micro-Focus X-Ray Fluorescence (µ-XRF) as an Extension of the Analytical SEM. Microscopy and Microanalysis, 16(S2), 904-905. doi:10.1017/S1431927610054115]
  4. Nichols, Monte C., Boehme, Dale R., Ryon, Richard W., Wherry, David, Cross, Brian, and Aden, Gary. Parameters Affecting X-Ray Microfluorescence (XRMF) Analysis. Advances in X-ray Analysis. 1986 Vol. 30, Page 45.
  5. Brian J. Cross, David C. Wherry, "X-ray microfluorescence analyzer for multilayer metal films," Thin Solid Films, Volume 166, 1988, Pages 263-272.
  6. Pozsgai, I. (1991), X-ray microfluorescence analysis inside and outside the electron microscope. X-Ray Spectrometry, 20: 215-223.
  7. X-Beam Polycapillary XRF
  8. Bruker Introduces Two New Analytical Accessories for Electron Microscopes

Advanced Elemental Analysis with ED-EPMA, WD-EPMA and µ-XRF at a SEM. V.-D. Hodoroaba, et al. Microscopy and Microanalysis 17:600-601, July 2011.

Comparing the detection of iron-based pottery pigment on a carbon-coated Sherd by SEM-EDS and by Micro-XRF-SEM. Michael Pendleton, et al. The Yale Journal of Biology and Medicine. 87(1):15-20, March 2014.

Micro-XRF excitation in an SEM. M. Haschke, F. Eggert and W. T. Elam. X-ray Spectrometry. Vol. 36, No. 4, p. 254-259 (2007).

Micro-XRF in Scanning Electron Microscopes. Michael Haschke and Stephan Boehm. Advances in Imaging and Electron Physics. Vol. 199, p 1-60, (2017).

A flexible setup for angle-resolved X-ray fluorescence spectrometry with laboratory sources. M. Spanier, C. Herzog, D. Grötzsch, F. Kramer, I. Mantouvalou, J. Lubeck, J. Weser, C. Streeck, W. Malzer, B. Beckhoff, B. Kanngießer. Review of Scientific Instruments, Vol 87, No 3, (035108), (2016).

Michael Haschke, Laboratory Micro-X-Ray Fluorescence Spectroscopy, Vol. 55 (2014).

Trends in environmental science using microscopic X-ray fluorescence. Ursula Elisabeth Adriane Fittschen & Gerald Falkenberg. Spectrochimica Acta Part B: Atomic Spectroscopy, Vol 66, No 8, p 567-580 (2011).

Determination of the real transmission of an X‐ray lens for micro‐focus XRF at the SEM by coupling measurement with calculation of scatter spectra. V.‐D. Hodoroaba & M. Procop. X-Ray Spectrometry, Vol 38, No 3, p 216-221, (2009).

Improvements of the low-energy performance of a micro-focus x-ray source for XRF analysis with the SEM Procop, Mathias; et al. X‐Ray Spectrometry: An International Journal 38.4 (2009): 308-311.

A microfocus X-ray source for improved EDS and XRF analysis in the SEM. Procop, Mathias, Vasile-Dan Hodoroaba, and Vanessa Rackwitz. Microscopy and analysis / European edition. p 10-13 (May, 2011).

X-ray fluorescence as an additional analytical method for a scanning electron microscope. Procop, M., Hodoroaba, V. Microchim Acta Vol 161, p 413–419 (2008).

Gaining improved chemical composition by exploitation of Compton-to-Rayleigh intensity ratio in XRF analysis. Hodoroaba, Vasile-Dan, and Vanessa Rackwitz. Analytical Chemistry 86.14 (2014): 6858-6864.

Pendleton, M. W., et al. Detecting iron-based pigments on ruthenium-coated archaeological pottery by SEM-EDS and by micro-XRF-SEM. Microscopy and Microanalysis 20.S3 (2014): 2030-2031.

Rackwitz, Vanessa, et al. Performance of μ-XRF with SEM/EDS for trace analysis on the example of RoHS relevant elements–measurement, optimization and prediction of the detection limits. Journal of Analytical Atomic Spectrometry 28.9 (2013): 1466-1474.

Sieber, John R., and Adam Mortensen. “Validation and traceability of XRF and SEM‐EDS elemental analysis results for solder in high‐reliability applications.” X‐Ray Spectrometry 43.5 (2014): 259-268.

Micro XRF Element Maps Are A New Method Of Detecting Elements At Lower Concentrations Than The Electron Beam Produced Corollary: A Garnet Schist Example.” Microscopy and Microanalysis 15.S2 (2009): 34-35.

Two commercial vendors offer this technology: