Why do wintergreen Life Savers spark when crunched'

'Most students of the modern Life Saver classify sparking as a type of triboluminescence, which occurs when something is crushed or torn, the something in this case being the hard crystalline sugar that Life Savers contain. . . .

Wintergreen sparking, it's believed, is actually a three-step process. Step One: When you shatter the sugar crystals with your teeth, electrons (which are negatively charged) break free. As a result, the atoms in which the electrons were formerly embedded become positively charged. In what amounts to a subatomic game of musical chairs, the free electrons dash around madly trying to find a new home.

Step Two: Meanwhile, as the sugar crystals disintegrate, nitrogen molecules from the air attach themselves to the fractured surfaces. When the free electrons strike the nitrogen molecules, they cause the latter to emit invisible ultraviolet radiation, along with a faint visible glow.

Step Three: The UV radiation is absorbed by the wintergreen flavoring, methyl salicylate. This then emits the fairly bright blue light you see. Pretty complicated, I admit.'

'Cecil Adams, from Why do wintergreen Life Savers spark when crunched', 'A Straight Dope Classic from Cecil's storehouse of human knowledge,' originally published on June 15, 1984.