
23.4 ABSORPTION SPECTROSCOPY
23.4.1 Introduction
Spectroscopy studies the way electromagnetic radiation interacts with matter.
When radiation meets matter, the radiation is either scattered, emitted, or
absorbed. This gives rise to three principal branches of spectroscopy. Emission
spectroscopy observes light emitted by atoms excited by radiation–matter inter-
actions. Raman spectroscopy monitors light scattered from molecules. Absorption
spectroscopy studies radiation absorbed at various wavelengths.
In absorption spectroscopy, light illuminates a sample of material to be
analyzed. The sample, which can be liquid, solid, or gas, is usually enclosed ...