Illustrated Glossary of Organic Chemistry

Quantized: In quantum mechanics, the concept that a system cannot have any possible energy value but instead is limited to certain specific energy values (states). The states depend on the specific system in question. That quantum mechanical energy states are quantized is a fundamental concept in infrared spectroscopy and NMR spectroscopy.

In NMR spectroscopy, the proton nuclear spin state is quantized. It has exactly two energy values: I = +1/2 (the ground nuclear spin state) and I = -1/2 (the excited nuclear spin state). The proton can never have an energy state less than I = +1/2, an energy state between I = +1/2 and I = -1/2, or greater than I = -1/2.