Wavelength Tech Forum: X-ray Spectroscopy


This month's Technology Forum looks at the topic of X-ray Spectroscopy and the trends and issues surrounding them. Joining us for this discussion are Dr Simon FitzGerald, from HORIBA Jobin Yvon, Dr. Kai Behrens, from Bruker AXS, Inc., and Peter LaPuma and Alexander Seyfarth, also from Bruker AXS, Inc.

A technique that has always held a lion’s share of the atomic spectroscopy market (X-ray techniques accounted for 40% of the market in 2007), X-ray continues to be a popular and powerful tool in the field of materials analysis. And with applications continuing to develop, along with the speed and sensitivity of the instrumentation, X-ray promises to be here for years to come.

In this month's Technology Forum, participants discuss trends in X-ray spectroscopy. Joining us for this roundtable are Dr. Simon FitzGerald, from HORIBA Jobin Yvon; Dr. Kai Behrens, from Bruker AXS, Inc.; and Peter LaPuma and Alexander Seyfarth, also from Bruker AXS, Inc.

What is the current state of the X-ray spectroscopy marketplace? What trends do you see emerging?

FitzGerald: There is continued strong demand for routine bulk XRF analyzers in many varied industries. However, an important new trend is the development of microscopic techniques – these couple the long appreciated benefits of XRF with analysis spot sizes as small as 10 micrometers. Thus it is possible to analyze individual particles or features, and (using motorized sample stages) generate detailed element distribution images across large areas of a sample. In a way these capabilities provide a crossover between x-ray analysis on an electron microscope (SEM-EDX) and more traditional bulk XRF techniques. They offer improved ease of use, sensitivity, and affordability compared with large SEM installations. This also matches growing demands from the general instrumentation market.

Behrens: The X-ray spectroscopy market is growing in the Asian/Australian region, where Europe and North America tend to decrease general investment into process and quality control instrumentation. The segment of smaller EDXRF is generally increasing, especially new technologies like small spot analyzers and handhelds.

LaPuma and Seyfarth: The mature market for WD and EDXRF is contrasted to the growing market of handheld and mobile systems. Most XRF sales in the ED and WD segment is production oriented and follows the general market, which this year is moving very cautiously. Demand for mining, petro, and high-tech materials drives demand for WDXRF. The regulatory driven expansion for ED in ROHS and green is leveling off.

Some trends seen in the personal computer sector are mirrored in the XRF segment. Smaller components enable more compact mobile and handheld systems, and these smaller systems continue to increase in popularity. The bundling of systems with applications, e.g. PETRO analyzer and Cement Analyzer, have increased throughout the industry. Also support, with respect to the application, is increasingly sought out.

We also see XRF knowledge diminishing due to fewer and fewer opportunities where users are able to learn about XRF. Bruker is intensifying the effort by offering online classes in XRF theory as well as financially supporting seminars and classes in conjunction with DXC, ICDD, and the University of Western Ontario.

Has X-ray spectroscopy changed much in the last 2 years? In what ways?

FitzGerald: There have been great strides made in making X-ray spectroscopy routine and easy to use, and this has seen large increases in applications and markets for XRF analysis. The development of low-cost handheld analyzers for bulk analysis with intuitive software have seen the number of people who use XRF spectroscopy increase dramatically. The use of XRF to monitor compliance of manufacturers to WEEE/RoHS regulations in Asia and Europe have seen sales of large numbers of both bulk and micro-analysis XRF systems; this demand for compliance is now starting to hit the US. Finally, there has been tremendous developments in the power of software for XRF spectra and image analysis with programs like Oxford’s INCA platform, allowing dramatic increases in the information that can be obtained from a sample.

Behrens: The market moved to smaller specialized units: handheld analyzers for RoHS, metals, recycling, RoHS-spot-Analyzers, as well as solution-oriented buyers, trace element analyis by TXRF.

LaPuma and Seyfarth:Production-oriented XRF systems have become network “appliances,” separating the user and the calibration and maintenance aspects. Less knowledge and inclination about calibration and validation of XRF on the client side has resulted in increased demand of turnkey systems, customized by the vendor. Application support onsite and remotely is a crucial factor for the client’s decision to buy. Smaller benchtop systems are becoming more powerful, with ongoing development to reduce size and increase capabilities.

What does the future hold for EDXRF?

FitzGerald: The future of EDXRF looks bright. The continued development of new detector technologies such as single and multi-element silicon drift detectors (SDD) presents significant advantages (spectral resolution, count rates, Peltier cooling) within EDXRF analysis. The maturation of the microscopic and handheld markets will also see EDXRF further move into new areas perhaps not traditionally associated with X-ray technology.

Behrens: Stronger, new advances in technology will make the units competing in more traditional fields of ICP, AAS, and conventional WDXRF.

LaPuma and Seyfarth: With the silicon drift detector of the 4th generation reaching the theoretical limit (FANO limit) of around 125 eV, the competition for higher and higher count rates will drive the development. However, very light element sensitivity needs to be balanced with the ruggedness of the detector window material. EDX has the potential of further growing market share, taking away traditional WDX markets. We expect more and more turnkey multi-application systems and the “appliance” approach.

How can X-ray spectroscopy be utilized in security or forensics situations?

FitzGerald: Micro-XRF is widely used within forensic and security analyses, since it can offer detailed qualitative and quantitative elemental characterization on very small amounts of sample. Case evidence for criminal investigations is often only present in microscopic quantities. Since it is usual that a number of different analyses will be made on a single sample, it is vital that the analysis is nondestructive. Unlike bulk XRF techniques, micro-XRF does not rely on sample preparation techniques such as fusion or milling, so it meets this criterion perfectly. The introduction of an expansive XRF library and database searching and archiving software, like SLICE from xk Inc., has made forensic analysis very routine. Specific areas which benefit include:

• Gunshot residues – XRF imaging reveals the pattern of the residue on textiles/skin, thus providing information on the distance of the gun from the victim. Spectral analysis of the individual particles within the residue can be used to learn more about the specific gun/bullet used, and to provide evidence that a gun was fired by a suspect.

• Paint cross sections – flaked paint from crash and crime scenes can be analyzed to understand their layered structure. Repaints and repairs over time can result in a unique “signature” of paint layers, so characterizing this can be used to link persons or vehicles to a particular crime scene. The layers are typically less than 100 micrometers thick, so a microscopic technique is vital for these analyses.

• Glass particles – commercial glasses contain a wide variety of trace elements, and their precise composition can be used to distinguish them. Tiny glass fragments (usually ranging from 50-300 micrometers) originating from a crime scene can be quickly characterized using micro-XRF.

• Security inks – many unusual heavy elements are included within inks used for bank notes and customs labels in order to make counterfeiting difficult. XRF analysis of such samples can quickly distinguish counterfeit from real, however good the visual match.

Behrens: It is already part of the analysis in crime scene investigations, identification of substances in customs, and more to come up.

LaPuma and Seyfarth: Forensics has a number of applications for XRF, mainly micro XRF and EDS. Mapping of gunpowder residues (both EDS and WDX) as well as trace element determination of drugs (fingerprinting) are standard applications. However, training and knowledge of the use of XRF has to be increased to reach a wider audience. Customs enforcement is an excellent example where XRF can help determine the nature of a material and help to check declarations, specification, and “taxing.” It also allows users to verify IF products comply to current or future regulatory requirements. Some examples include: What type of ore is in the containers? Pb-free plastics? Fuel with declared S value allowed in the ship? This market again will be driven by more and more mobile, portable, and handheld systems; however, each customs location has at least has one “big” WDXRF as well.

Where do you see the state of X-ray spectroscopy 10 years from now?

FitzGerald:X-ray spectroscopy will continue to be a very important tool for analysts in many different fields – instrumentation manufacturers will continue to strive for improved sensitivity, affordability, and ease of use. Ten years from now there are likely to be many more analysts using X-ray spectroscopy, whether in handheld portable devices, benchtop systems, or microscopes – some probably won’t even be fully aware that their analysis depends on X-rays! The continued drive for combined analytical techniques will surely result in systems where X-rays and other spectroscopic techniques offer more information through a single instrument. XRF microscopy is a very powerful yet under-utilized technique. In the future, there is no reason why the number of XRF microscopes being used could not be the same as the number of FT-IR or Raman microscopes.

Behrens: Strongly growing because users are more and more afraid of acid-based dilutions for traditional labor-intensive optical methods.

LaPuma and Seyfarth: XRF will be very much alive and kicking. Customers will be using more and more turnkey applications and compared to today there will be an increased market share of EDX. New players will change the competitive landscape, as well as create a large potential for more consolidation. Smaller systems will dominate the sales numbers, and floor standing units as we know them today will become an exception.

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