Resonance and ionisation potentials for electrons in cadmium vapor

Abstract

The phenomena connected with the passage of electrons through mercury vapor have been fairly completely investigated. Franck and Hertz ^ have shown that when the velocity of the electrons is less than that attained in falling through 4.9 volts there is no loss of energy at impact with a mercury atom. After falling through a difference in potential of 4.9 volts, however, the electrons are capable of transferring all of their kinetic energy to the mercury atom. The energy absorbed by the atom under these conditions is emitted as radiant energy of the single wave length, X = 2536.72A. It was at first thought that this radiation of light was the result of a recombination with the atom of an electron which had been removed from it by the energy of impact. That