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 Montpelier Magazine

        

This Little Light of Mine

EVER SINCE THE ANCIENT GREEKS first speculated that atoms might be the one natural element underlying all things, dedicated scholars investigating a subject have sought illumination. Upon attaining such enlightenment -- in sacred or secular studies -- some have been regarded as illuminati or, as a group of 18th-century German rationalists dubbed themselves, Illuminati,with a capital I. Today, however, chemistry professor Benjamin DeGraff literally uses illumination to investigate subject matter. DeGraff shoots lasers into molecules he has customized so that they "luminesce" or glow. The quality of that "luminescence" in turn sheds light on a host of environments that the professor is exploring on behalf of science and industry.

The more recent half of DeGraff's 30-year career at JMU has been devoted to re-searching and creating molecules and illuminating students about lasers. And his early efforts to bring lasers and the cool things they do into the undergraduate classroom have earned him glowing honors from colleagues and former students in the American Chemical Society, most recently at a national symposium last year.

Lean and trim, as befits a person dealing with lasers, the goateed DeGraff is quiet but personally warm and enthusiastic about his research. Direct and focused, he does not digress or grow diffuse as he speaks. If he were a laser, he would tend toward the warm reddish end of the spectrum.

The impact of laser technology within science -- and domestic life (if there's a couch potato, there's a laser near at hand) -- has been seismic. Although much like the personal computer, the professor says, the laser has been "a much quieter revolution than the PC." Nonetheless, the laser has been as momentous an advance to science as the development of the microscope. In both instances, scientists acquired the means "to look at new things, which were simply not acces-sible before," DeGraff explains with the measured ease and habitual devotion of a pioneer who has synthesized the early excitement of chaos and possibility into focused, proven lessons and advances in his field.

In the case of lasers, however, a scientist is not exactly "seeing" a mol-ecule. "That's one of the frustrations that chemists always have," the professor says. "We see images of molecules, sort of ghostly renditions of them. But what lasers allow us to do is carry out experiments on a very, very fast time scale," such as a picosecond, DeGraff says. "That's the scale on which many chemically interesting events happen" at the molecular level. That's why he is interested in building special mol-ecules for special occasions.

A molecule, when struck by a laser -- DeGraff calls it "probing or interrogating" -- glows or "luminesces." The quality of that luminescence -- its color, brightness or duration -- is, in essence, the molecule's "report" on its environment. Recognizing the utility of such reporting, DeGraff has spent much of his career exploring the world of "molecular reporters" and lasers. And interest in these luminescent "sensors" or reporters has "just blossomed" during the past few years, as government and corporate institutions have also begun to realize that molecules can report on some environments more quickly, accurately, economically, safely and comprehensively than can traditional means, DeGraff says. Consequently, both public agencies and private companies are turning to scientists like DeGraff to supply molecular reporters for specific applications.

Such applied research in academic science, DeGraff acknowledges, represents a trend away from the days when he first entered the profession (he came to JMU in 1972). Then lone scientists often worked in isolation on theoretical problems. But, as DeGraff sees it, "I've come to really appreciate when something has a direct application that might actually be doing some good for somebody." As an example, he cites his current research project to develop pH sensors, which could prove extremely beneficial to fish farmers, as well as environmental agencies.

Specifically he is seeking a molecular reporter that can indicate the specific acidity or alkalinity -- the pH -- of water, which could lead to significant improvements in how water quality is monitored. As DeGraff explains, "Right now, the way most water monitoring is done in this country is somebody gets to trudge out to wherever the water is and scoop up plastic bottles and bring them back to the lab" for analysis. The trouble with this system, DeGraff points out, is that it takes an army of field technicians and requires time.

"It would be really cool if you didn't have to do that," the professor says, because sometimes slight changes in the pH of a river, lake or estuary can produce a sudden and deadly bloom of algae. In such cases, time -- meaning a day or even a few hours -- can be a criti-cal factor in preventing such a bloom. And prevention can mean the difference between losing or saving the lives of thousands of fish and safeguarding a region's environment, as well as its recreational, tourist and fish-to-market dollars. The ideal scenario, DeGraff says, would enable a few technicians in a central hub to monitor the water quality throughout a large geographical area - say, an entire state - "in real time."

One possible way to achieve that scenario would be to disperse buoys containing special pH-sensitive mol-ecules embedded in a polymer at the end of a fiber optic cable. If the mol-ecules are left to dangle in the water, a laser can travel down the cable, causing the reporter molecule to luminesce. The return molecular glow is detected and converted into information that then can be beamed to a satellite that transmits it to a centrally located monitoring station. Thus whenever a monitoring technician -- who may be hundreds of miles away -- needs an update on a particular water point, she can trigger the laser and interpret the results.

"So," DeGraff says with enthusiasm, "we're working on [developing] luminescent materials that change their luminescence -- their color, their brightness or their duration -- as a function of pH." His research on the project is being coordinated with colleagues at other institutions, who work as teams assigned to various aspects of

the problem. One team, therefore, is concerned with developing the teleme-try or data-relay piece of the puzzle,

while another is focusing on the optic piece -- getting laser light down and luminescence back up the cable. DeGraff is working with the University of Virginia's James N. Demas to synthesize the "sensor" molecule and the polymer in which it is embedded.

Although constructing these molecules is highly complex, DeGraff's explanation is not.

"We construct or synthesize our molecules much as you would build a home sound system," the professor says. "Seldom do you start with chips, resistors and wires, but rather ... with modules such as speakers, amplifiers, CD players."

DeGraff and Demas usually pick modules or parts of molecules that already possess the properties they ultimately want and then modify them into the desired fragments.

"When we have made all the fragments," DeGraff explains, it's "like coming home from Circuit City with a trunk full of components. ... Just like the home sound system," he adds, "things can still go very wrong when you try to hook them up. Also, the sound quality may be quite different than you had hoped for, even though you used very good modules. So we often find that even after careful assembly of what we thought were the right fragments or components, the final molecule does not function as we had hoped. If we are lucky, 20 to 30 percent of our final molecules have the properties that we were aiming for."

DeGraff's successful molecules then re-spond to the light that emanates from the lasers he teaches in his own classroom.

"Laser" is really an acronym for Light Amplification by Stimulated Emission of Radiation. Knowing or not knowing the acronym may say a lot about where you first encountered lasers. The devices worked their way rapidly from secret Cold War re-search lab settings in the 1960s to rock concerts by the early 1970s and some household gadgets by the 1980s. But their common occurrence in research labs by the early '80s also meant it was imperative that undergraduate chemistry and physics students gain familiarity with them.

Keeping ahead of the wave in undergraduate education, DeGraff by the mid-1980s began offering JMU students an introductory laser course aimed at teaching them the fundamental aspects of the technology. At that time, JMU was among only two or three universities nationally that were offering such opportunities to undergraduate students. "Now," says DeGraff, "[there are] probably about 40 universities throughout the country doing this kind of thing."

DeGraff can take some credit for the increased dispersion of laser instruction in undergraduate programs. In 1987, he began offering an intensive, one-week, hands-on summer workshop to colleagues from other institutions to teach them about lasers and how to incorporate them into the classroom. Sponsored by the National Science Foundation and limited to about 15 students per session, the workshops apply lasers "to really interesting experiments which will tell us more about the microscopic universe in which we live," says DeGraff. During the 11 summers of workshops, he estimates that he has instructed more than 130 professors from 40 states.

"Some measure of our success," DeGraff says of the workshops, "has been that a big fraction of the proposals that NSF gets for new laser-related instrumentation from undergraduate institutions are from people who have been to our short course." As a gesture of thanks for his efforts to teach teachers about using lasers, DeGraff's colleagues and former students honored him at a Division of Chemical Education symposium during the American Chemical Society's national meeting in Washington, D.C., in 2000.

The soft-spoken professor becomes animated when talking about his research, which is supported by funding from NSF, as well as corporations that contract through JMU. A Northern Virginia company, for in-stance, is funding his research to synthesize the sensor molecule for pH. Previously, Ford Motor Co. supported DeGraff and Demas' work when the company sought remedies to reduce wind noise in moving automobiles.

In that work, DeGraff and Demas created a luminescent material that Ford painted on a model prototype of one of its cars. The car was then placed in a tunnel through which wind blew at up to 200 mph. The luminescent sensors responded in relation to the differences of barometric pressure across the car's surface. In this way, engineers were able to determine just exactly where the car met with less or more wind resistance, and, using computer modeling, they were able to modify the design accordingly. (Most wind noise, it turns out, is caused by side mirrors, DeGraff says.)

DeGraff cannot imagine another creative life for himself other than one divided be-tween teaching and research. The only difference, he admits, is if he could start again in the sciences he would learn more about physics, which he "has had to learn on the fly" as he is "not mathematically inclined."

When he is not in the lab or the classroom, DeGraff recharges himself by canoeing, skiing, hiking -- any activity that gets him outdoors, which may help explain his youthful vigor. It's during those times he often lights on new ways to resolve specific problems he has been wrestling in the lab. And though he is not quite ready to retire, he looks forward after a few more years to getting loose from the classroom and lab so that he can travel with his wife and spend even more time outdoors. After JMU, he would love to live in the Cascades. Then a thought strikes -- he would love to try sea-kayaking in the Pacific northwest -- something he has yet to do. As he strokes his beard, at the thought of replacing light waves with ocean waves, you can just sense he's beginning to luminesce.

Story by Randy Jones, Photos by Diane Elliott ['00]