1962 Volume 35 Issue 2 Pages 218-224
The distribution curves of the kinetic energis of secondary electrons from the activated copper-beryllium surface impacted by inert gas ions were together with the yield of the secondary electrons, measured by the retarding potential method. The contact potential difference between the ion target (activated copper-beryllium) and the electron collector (gold) was also measured by the retarding potential method for the thermal electrons from tungsten, and the correction to the kinetic energies of secondary electrons by this contact potential difference was made. For the purpose of obtaining information about the emission characteristics of the increase in the yield ot secondary electrons by target activation, the distribution of ΔN0(Ek), which is the difference in the secondary electrons emitted from activated and from electro-polished copper-beryllium, was plotted by electron energies. The main results obtained are as follows:
(1) The contact potential difference between activated copper-beryllium and gold is 0.25 eV. (gold, negative).
(2) The general features of the distribution curves of the secondary electrons emitted from activated copper-beryllium show a tendency similar to that of the secondary electrons emitted from electro-polished copper-beryllium, and they also show a great similarity to the distribution curves obtained from the not atomically clean semiconductor surface (germanium or silicon) by Hagstrum.
(3) The distribution of ΔN0(Ek) show a remarkable difference from the distribution curves for activated copper-beryllium. Distribution curves of ΔN0(Ek) higher than about 4eV. in electron energies showed a great similarity to the distribution curves of the Auger electron obtained by Hagstrum. Moreover, the distribution of ΔN0(Ek) for singly-charged ions shows clearly a separation in the electron energy scale; this result was explained by the fact that the stopping cross-section of the beryllium oxide is greater than that of the cupric oxide.
(4) From the explanation of the distribution of ΔN0(Ek), it is considered that the increase in the yield of secondary electrons by target activation depends on the stopping cross-section of beryllium oxide and on the Auger process of electron emission.
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