Photochemical reactions begin by absorption of energy in the form of light, and involve formation of free radicals and transient excited states whose physical and chemical properties are very ...

Why does plastic turn brittle and paint fade when exposed to the sun for long periods? Scientists have long known that such organic photodegradation occurs due to the sun's energy generating free ...

Slow spectroscopy The experiment was able to detect the extremely faint, long-timescale signals emitted by luminescent materials. This material is illuminated by a laser and the faint signals long ...

Your fancy white electronic brick of consumer electronics started off white, but after some time it yellowed and became brittle. This shouldn’t have happened; plastic is supposed to last forever. It ...