Introduction by Frank Hertz

Frank-Hertz experiment provides direct evidence for the existence of energy levels and is a strong support for Bohr's atomic theory. Frank is good at the experimental study of low-pressure gas discharge. 19 13 collaborated with G. Hertz at the university of Berlin to study the relationship between ionization potential and quantum theory. The method used is the reverse voltage method created by Learnard, from which they obtain the ionization potentials of a series of gases, such as helium, neon, hydrogen and oxygen. Later, they specially studied the collision characteristics of electrons and inert gases.