The variation of secondary emission with heat treatment

The ratio of the number of electrons striking a surface to the number leaving it was determined under various conditions for a number of metals contaminated by the condensation of grease vapors on them.The curves showing the variation of secondary emission with incident electron energy (evidently characteristic of the contamination rather than of the metals) are similar for all the targets and resemble the results obtained by Gehrts. Reducing the amount of the contamination by heating the metals at first reduces the secondary emission until it falls below that expected from a clean metal. The emission then increases with further heating and the characteristics of the metal appear. The variation of the work function during the “outgassing” process is indicated by this increase of the secondary emission followed by a decrease of the secondary emission as the process continues.