Cathodoluminescence of Strontium Oxide, Barium-Strontium Oxide, and Magnesium Oxide

Abstract

A survey of some spectral and time decay properties of the cathodoluminescence of SrO, (BaSr)O, and MgO samples has been made in sealed-off high-vacuum tubes in the spectral range from 220 m\ensuremath{\mu} to 600 m\ensuremath{\mu}. Observations were made for sample temperatures varying from 90\ifmmode^\circ\else\textdegree\fi{}K to room temperature and above with the samples in different states of thermionic activity.In SrO samples, luminescence maxima were observed at photon energies of 4.9 ev, 3.7 ev, 3.2 ev, and 2.4 ev. The 4.9-ev band intensity increases with the thermionic activity of the sample whereas that of the 3.2-ev band decreases.Emission band maxima were found in (BaSr)O at energies of 4.0 ev, 3.1 ev, 2.6 ev, and 2.1 ev. A comparison of the (BaSr)O luminescence is made with that from SrO and BaO.MgO samples were studied in both polycrystalline and single crystal forms. Luminescence band maxima were observed at energies of 5.2 ev, 3.6 ev, 2.7 ev, 2.3 ev, and 2.1 ev. The 2.3-ev band may be enhanced by heating the sample in magnesium vapor or diminished by heating it in oxygen.Suggestions are made concerning possible electronic mechanisms giving rise to some of the above bands on the basis of the temperature dependence of their intensities and their types of afterglow.