X.—On the Quantum Mechanism in the Atom

Abstract

It is now well established experimentally that when an atom is caused to emit radiation of frequency v by collision with an electron, the amount U of the kinetic energy of the electron which is absorbed by the atom is given by the equationwhere h denotes Planck's quantum of Action : an electron whose kinetic energy before the encounter is less than hv is incapable of stimulating the atom to emit the radiation, and is merely repelled from the atom without any loss of energy.