The U.S. Department of Energy is bursting with, well, energy, now that its new secretary, Steven Chu, has been sworn in.

Six of my colleagues at the American Association for the Advancement of Science have fellowships at Energy. I spoke to one, who thought that this appointment makes a positive statement about Obama’s approach to energy policy. If Obama had appointed oilman turned alternative energy and natural gas promoter T. Boone Pickens, for example, that would have set a different tone, as would the appointment of a lawyer, or a businessman tied to the energy sector.

Chu’s appointment to the Cabinet-level position of energy secretary means a “scientist has a voice in the Cabinet,” my colleague said. Obama also can consult with John Holdren, the scientist appointed to direct the White House Office of Science and Technology Policy.

Chu won the Nobel Prize in physics in 1997 for using lasers to cool and trap atoms. In the ensuing decade he has been an outspoken advocate of renewable energy sources. He formerly headed the Lawrence Berkeley National Laboratory, overseeing 4,000 employees and a $650 million budget – so he’s no stranger to government bureaucracy. As a scientist in academia (he spent some of his career at Stanford), he realizes the importance of government funding for basic research.

Normally Science Planet focuses on cutting edge life science research, but I couldn’t resist discussing this gem: physicists from the University of California in Los Angeles (UCLA) discovered that peeling Scotch tape emits bursts of X-rays so plentiful that scientists were able to capture an X-ray image of a human finger.

In 1939 Princeton University scientist E. Newton Harvey wrote in the journal Science that “most experimenters have observed the transient greenish luminescence which occurs at the point where electricians or surgeons’ or ‘Scotch’ tape is stripped from a roll.” In other words, peeling tape produces light. In an airless chamber, a vacuum, the phenomenon becomes much more energetic, releasing high-energy X-rays in addition to visible light — according to a 1953 report from researchers in the then Soviet Union.

The Russian work met with skepticism and wasn’t rigorously pursued.

The phenomenon of producing light from mechanical energy — rubbing, breaking, crushing, or peeling something — is known as triboluminescence (from the Greek tribein, to rub, and the Latin lumen, light). Cool examples of triboluminescence: diamonds sometimes glow when cut; crushing sugar crystals generates sparks of light. In a dark room, bite or crush a hard sugar candy, like Wint-O-Green Lifesavers, and you’ll see triboluminescence.

It was in a dark room that UCLA postdoctoral fellow Carlos Camara first realized that the Russian group might have been on to something. Camara told me that he and graduate student Juan V. Escobar were studying triboluminescence using mica, a mineral known to emit light when split. Under a vacuum, breaking mica produces X-rays. Camara was standing in the dark using adhesive tape to peel away layers of mica to produce light and he noticed that simply peeling the tape, in preparation for applying a piece to the mica, produced a much brighter light than the mica. If peeling the tape under normal conditions produced a lot of light, Camara thought, would peeling the tape under a vacuum produce a lot of X-rays?

The answer was yes. Working in the laboratory of Seth J. Putterman, Camara and colleagues built a device to unroll tape at 1.2 inches per second and measured the X-rays produced, which were bright enough to generate an X-ray image of a finger. They also found that X-rays are produced in bursts and continue to be released during ten rewindings of a single roll of tape.

X-rays are only produced when tape is peeled in a vacuum, so there is no danger of radiation exposure when using tape in your office. According to Camara, X-ray emission is not specific to Scotch tape. Other types of adhesive tape, such as Magic tape, also produce X-rays.

Camara is excited about potential future applications, notably providing a new X-ray source for medical imaging. Harnessing the power of tape may one day allow physicians to capture X-ray images without an expensive, high voltage power source. Such a device could provide the diagnostic power of X-rays to people living in remote communities who are unable to travel to a regional clinic.

Do you have ideas for other potential applications of X-rays from adhesive tape?

Source: “Correlation between nanosecond X-ray flashes and stick-slip friction in peeling tape” by Carlos G. Camara, Juan V. Escobar, Jonathan R. Hird and Seth J. Putterman, published in the October 23 issue of Nature.