Positive Surface Ionization of Na, NaCl, NaBr, NaI, and LiCl on Rhenium and on Oxygenated Rhenium Surfaces

Results are reported for the ionization of sodium, sodium halides, and lithium chloride on rhenium and on oxygenated rhenium surfaces. The oxidation of a rhenium surface was found to cause an increase in its work function. As a result the ionization efficiencies for sodium and sodium halides incident on this surface are increased from about 0.20 to unity. The efficiency for lithium chloride is also increased to a value probably close to unity. The oxide layer which is formed even at low air pressures (5 × 10−7 torr) seems to be stable only up to about 1650°K.