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Windows of opportunity: synchrotron opens new windows in chemical analysis.

When Saskatchewan uranium mining companies Cameco and COGEMA Resources needed to prove arsenic in their railings treatment streams was being dealt wit]] properly-they turned to synchrotron analytical techniques.

"The requirements of our tailings preparation process are drivel] by satisfactory long-term performance," says John Rowson, COGEMA's director of McLean Regulatory Affairs.

"I'm talking about thousands of years in the future. There was really no other technique available in the world that would determine the structure of the arsenic precipitates."

For Brett Moldovan, senior metallurgist with Cameco's Key Lake mine and PhD candidate, the potential for synchrotron analysis of arsenic mine wastes began with an invitation in 1999 to participate in a collaborative project with the University of Saskatchewan (U of S) and the Canadian Light Source (CLS) in Saskatoon. The U of S-owned synchrotron project had just been launched with a strong mandate to serve industry as well as academic and government research.

Moldovan worked with CLS staff scientists De-Tong Jiang and Jeff Cutler, MCIC, as well as U of S geology professor Jim Hendry at the Advanced Photon Source synchrotron in Chicago to work out the analytical techniques. They offer great advantages over existing methods.

"It's orders of magnitude more sensitive than conventional techniques," he says. "Cameco is using synchrotron light as a tool to understand the valence states and coordination chemistry of arsenic in uranium mine tailings. This information will ultimately be used to determine the long-term evolution of arsenic in the tailings."

Analyzing environmental arsenic is one of many applications of the CLS, due to open this fall on the U of S campus.

Like the 40 or so other synchrotrons around the world, the CLS accelerates a stream of electrons. This hair-thin beam travels at nearly the speed of light around a ring-shaped vacuum chamber about as thick as a man's wrist. Powerful electromagnets built around this stainless steel pipe keep the electrons moving around the ring.

The electrons give off a brilliant flash of laser-like light every time they are forced to change direction. This synchrotron light is produced in all frequencies from infrared through visible light to X-rays. This light is guided through beamlines to end stations where scientists perform a wide range of experiments.

Synchrotron light allows scientists to study everything from molecules for better medicines to oil additives that will extend the life of vehicle engines. It can be used to find out if ancient artifacts are real or forgeries, to study how food plants react to frost, or to track contamination in groundwater from livestock operations.

University of Western Ontario (UWO) chemistry professor Michael Bancroft, FCIC, has been using and promoting synchrotrons for research for more than 30 years. He led the team that proposed the Canadian synchrotron be built at the UWO. His group threw their support behind a joint effort with the U of S once the Prairie proposal got the green light. Bancroft also served as CLS director and continues to serve as special consultant to the current executive director.

Bancroft recalls his first experience in 1975 with synchrotron-based X-ray photoelectron spectroscopy, at the time a relatively new technique.

"Even then it enabled me to do higher resolution work than you could do in a lab," he says. "As synchrotron light sources got better, we could do much higher resolution work."

Protein crystallography is an example. In this field, researchers grow crystals of purified proteins. Then they use X-rays to examine their shape and structure. The information guides the design of new drugs and therapies for diseases such as diabetes and high blood pressure.

Crystallographers have lab sources of X-rays to use in their work. But proteins are notoriously hard to get into crystal form, and bigger crystals are harder to make.

"To get atomic-scale resolution, or if you have very small crystals, you have to go to a synchrotron," Bancroft says. "You can get crystal structure from a five by five-by-five micron crystal--that's about a tenth the width of a human hair. You need a microscope just to see the things."

The Canadian Macromolecular Crystallography Facility (CMCF), the CLS beamline devoted to this type of work, is slated for completion this fall.

Bancroft's own research into the engine oil additive zinc dialkyldithiophosphate (ZDDP) shows that it decomposes to form a microscopic film of extremely durable zinc polyphosphate patches, providing excellent wear protection. The CLS X-ray line suited to this research is the spherical grating monochromator-plane grating monochromator (SGM-PGM) beamline, due to come on-line this spring.

U of S professor of physics and Canada Research Chair Alexander Moewes is also interested in getting a high resolution look at new materials, but for a different purpose. He uses synchrotron light to determine- electronic structure. This structure governs, among other properties, how materials conduct or resist the flow of electrons--electricity.

An example is gamma silicon nitride, an exotic material that rivals diamonds in hardness. First synthesized in 1999, the compound is not easy to make, requiring extremely high temperatures and pressure. Analyzing it is also a problem, as most of it is in amorphous form--the opposite of the crystalline "pure phase" state that physicists normally need to determine electronic structure.

"It creates problems when you have the material as a powder but not in crystalline form," Moewes says. "Gamma silicon nitride is such a new material that there is essentially no crystal form available for analysis. ""

Using synchrotron-based techniques, Moewes and his team successfully described the substance's electronic structure and how this structure could be tailored by "doping" the substance with aluminum oxide. Using this method, Moewes can test material characteristics at a very early stage, eliminating blind alleys and illuminating promising directions for applications such as ultra-durable electronic components.

The non-invasive nature of synchrotron analysis is proving valuable to U of S Canada Research Chairs Graham George and Ingrid Pickering. The husband and wife team, together with Australian chemist Hugh Harris, have found that we may have to rethink current models of mercury toxicity in fish.

Depending on its form, mercury can be relatively benign or extremely poisonous, as is the case with some types of methylmercury. While fish is highly nutritious and an important source of nutrients such as omega-3 fatty acids, it can become contaminated with mercury from industrial waste or other environmental sources. This is especially troubling for pregnant women, as mercury attacks the nervous system, and their developing babies are especially vulnerable.

The team examined samples of swordfish and orange roughy bought at a local fish market near the Stanford Synchrotron Radiation Laboratory in California, where both Pickering and George were based before their move to the U of S in 2003.

With conventional analysis, fish tissues need to be chemically pulled apart, which changes the sample. Using the synchrotron, the researchers could measure the intact sample and observe the mercury compounds directly, unaltered. In this case, they found the methylmercury was bound to a sulfur atom, likely making methylmercury cysteine. This form is less toxic in some animals.

"There's reason for cautious optimism that mercury in fish may not be as much of a concern as we thought," George says, although he stresses that more work remains to be done.

Pickering is focusing synchrotron light on another element, selenium. Unlike mercury, which has no known metabolic function, selenium is an essential nutrient, necessary in small amounts but toxic at higher levels.

Pickering is looking at a hardy plant of the North American Plains known as locoweed for its effect on cattle who eat too much of it. The plant is a selenium hyperaccumulator, that is, it takes the element from the soil and concentrates it in its tissues.

"These hyperaccumulators store a huge amount of selenium," Pickering says. "That is of interest if you have a high selenium area and you want to clean it up."

Using synchrotron-based X-ray absorption fine structure spectroscopy (XAFS), Pickering is examining where the plant is storing selenium and to what form. The XAFS beamline at the CLS is due for completion late in 2004.

Pickering's work could lead to applications in the emerging field of phytoremediation--using plants to clean contaminants from soils. It could also lead to enhanced nutrition for areas in the world where people struggle with selenium-poor diets.

These applications may be years away. However, U of S assistant professor of chemistry Stephen Urquhart, MCIC, says applied research has to be balanced with purely "curiosity-driven" work.

A fundamental question Urquhart is pursuing has to do with chiral molecules. Such molecules exhibit a "handedness." Like our hands, the mirror image of these molecules is not superimposable.

"These molecules are important in both chemistry and biology," he says. "For example, the amino acids that make up all living matter are nearly all of one handedness."

Chiral molecules have been studied with infrared, visible, and ultraviolet light. Urquhart wants to see what they look like in the X-ray range of the electromagnetic spectrum. The CLS soft X-ray spectromicroscopy (SM) beamline, due to come on-line this fall, is suited for this work.

"What I'm curious about is what happens when you use circularly polarized X-rays. Is the physics different or the same at X-ray wavelengths? There are arguments for both, but until we look at this question, we just don't know."

There is much to be Darned on the other side of the spectrum as well. This is the realm of Kathy Gough, MCIC, professor of chemistry at the University of Manitoba. She will work on the Mid IR beamline, one of two infrared beamlines at the CLS due to receive synchrotron light this summer.

Gough, a physical chemist, uses infrared light to look at scarring in various tissues such as that caused by heart attack, surgery, or burns. While there are bench top infrared sources for this work, they cannot match the speed and data quality possible with a synchrotron.

"The point of the synchrotron is that you get light about 1,000 times brighter and it is concentrated in a very small spot," she says. "We can illuminate a five-micron spot on a tissue sample and get really good data in a matter of seconds."

These five-micron scans can be combined into "pixels" of a bigger picture. Since the signal contains information from all molecules in the sample, Gough can look for differences as she traverses this image.

The power and versatility of synchrotron light as a research tool has gained the CLS unprecedented support. All three levels of government--federal, provincial, and municipal--pooled their resources to get the project off the ground in 1999, and continue to do so today.

With the approval in March 2004 of $18 million in funding front the Canada Foundation for Innovation, the $173.5-million national synchrotron facility is already planning a $44.5-million round of expansion. This will add five new beamlines, bringing to 12 the number in progress or planned. The CLS has room for 30.

Most recently, the government of Canada beefed up the CLS operating budget with a five-year, $1%million grant.

"We're delighted with the commitment we've seen from our country's leaders to ensure the Canadian Light Source enters the global synchrotron community as a truly world-class facility," says CLS executive director Bill Thomlinson. "These resources give us the capacity to recruit top scientists and provide the support national and international users need to perform leading research."

Already, there is evidence of a "brain gain," of researchers from Canada, the U.S. and abroad. When the CLS project was launched, only a handful of Saskatchewan researchers used synchrotrons. This group has grown to about 80 at the University of Saskatchewan alone.

27 universities across the country endorse the CLS project, and many Canadian researchers are already looking forward to using the facility, as it will reduce or eliminate the need to book time on foreign synchrotrons, or to move samples across international borders. The first call for research proposals will go out this fall.

To learn more about Canada's synchrotron or to book a tour of the facility, visit www.lightsource.ca.

Michael Robin is a science writer and communications strategist based in Saskatoon, SK. He is currently a research communications officer with the office of the vice-president research at the University of Saskatchewan. He can be reached at michael.robin@usask.ca.
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Comment:Windows of opportunity: synchrotron opens new windows in chemical analysis.
Author:Robin, Michael
Publication:Canadian Chemical News
Article Type:Cover Story
Geographic Code:1CANA
Date:Jun 1, 2004
Words:2044
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