The Interaction of Light with Matter
The interaction of light with matter is one of the most fundamental processes that occurs in nature. It is happening around us constantly: when we look up at the sky and see that it looks blue, when we look at the straw in our water glass and see that it looks bent, when we look up at the neon lights in Times Square and see their distinctive glow, we are witnessing the ever-present interaction of light with matter. This same interaction is at the core of some of science’s most advanced experiments, where lasers are used to trap single atoms or uncoil strands of DNA. It is also relied upon routinely in airports and laboratories to help distinguish the potentially innocuous from the noxious or illegal. Not a moment goes by when this most basic of interactions does not affect our lives in some way.
At its most basic, the interaction of light with matter entails the interaction of a single atom with a single quantum of light, called a photon. When an atom interacts with a photon, one of two things happen: it either absorbs (and later re-emits) the photon or it scatters the photon. Click here to read more about scattering and absorption.