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Angular Momentum and Electron Impact

Published online by Cambridge University Press:  24 October 2008

P. M. S. Blackett
Affiliation:
King's College

Extract

1. There seems to be little doubt that the detailed mechanism of ionisation or excitation by electron impact will not admit of description, even to a first approximation, by the system of classical mechanics. However the experimental work of Franck and Horton and their collaborators, has shown that, within the limits of the error of experiment, an electron is able to impart the whole or part of its kinetic energy to the atom it excites. When its initial energy is greater than the excitation energy, the electron, instead of being brought to rest, retains the excess as kinetic energy.

Type
Research Article
Copyright
Copyright © Cambridge Philosophical Society 1924

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References

* This fraction F (a) has been called by Hertz, the Efficiency of Inelastic Collision (Prot. Amst. Acad. 03 25, 1922).Google ScholarKlein, and Rosseland, (Zeit. für Phys., 4, p. 46, 1921)CrossRefGoogle Scholar defined a quantity so that the probability that an atom would be switched in unit time from a state 1 to a state 2, is equal to multiplied by the number of atoms in state 1 and by the number of electrons of energy ε. Since G(a) is merely an upper limit, we have the relation

in which ν is the velocity of the electron of energy e = E 0(1 + a 2).

* Bohr, , Ann. der Physik, 71, p. 286, 1923.Google Scholar

Franck, and Knipping, , Zeit. für Phys., 1, p. 321, 1920.Google Scholar

Franck, and Einsporn, , Zeit. für Phys., 2, p. 18, 1920.CrossRefGoogle Scholar

* The line (m=j) and the plane (m=0) are included as limiting cases of cones.

* Rubinowicz, , Phye. Zeit., 19, p. 441, 1918.Google Scholar