X-rays made from Scotch tape

UCLA physicists demonstrated that if you pull off a piece of Scotch tape inside a vacuum chamber, the tape releases enough X-rays to image bones through skin. Grad student Juan Escobar and his colleagues managed to make an X-ray of a thumb using the technique. (Composite image, including the thumb X-ray, below.) Apparently, Russian scientists reported fifty years ago that the act of peeling sticking tape can emit X-rays, but the new research confirms the early results. The latest experiments are presented in this week's issue of the journal Nature. From Nature News:
 News 2008 081022 Images News.2008.1185-2 "At some point we were a little bit scared," says Juan Escobar, a member of the research team. But he and his co-workers soon realized that the X-rays were only emitted when the kit was used in a vacuum. "We don't want to scare people from using Scotch tape in everyday life," Escobar adds.

This kind of energy release – known as triboluminescence and seen in the form of light – occurs whenever a solid (often a crystal) is crushed, rubbed or scratched. It is a long-known, if somewhat mysterious, phenomenon, seen by Francis Bacon in 1605. He noticed that scratching a lump of sugar caused it to give off light.

The leading explanation posits that when a crystal is crushed or split, the process separates opposite charges. When these charges are neutralized, they release a burst of energy in the form of light.
Sticky tape generates X-rays(Thanks, Bob Pescovitz!)