American physicist who, with his colleague Clinton Joseph Davisson (Davisson, Clinton Joseph), conducted an experiment (1927) that first demonstrated the wave properties of the electron. This experiment confirmed the hypothesis of Louis-Victor de Broglie, a founder of wave mechanics, that the electron should show the properties of an electromagnetic wave as well as those of a particle.

Germer was a graduate student at Columbia University, working under Davisson's supervision at the Bell Telephone Laboratories in New York City, when they bombarded a single crystal of nickel with an electron beam and observed that the distribution of the scattered electrons conformed closely to the prediction of de Broglie's hypothesis.