The energy spectra of secondary electrons from carbon, beryllium, aluminum, nickel, copper, barium, platinum, and the oxides of beryllium, aluminum, nickel, copper, and barium have been measured with equipment of high stability and sensitivity. Characteristic peaks due to Auger electrons emitted as a result of absorption of a valence electron by an excited x-ray level were observed for all these materials.

The peaks exhibit structure which is of some theoretical interest. The structure can be related to the distribution in energy of electrons in the valence band, and it complements that observed in soft x-ray emission work. Since the emission of the Auger electron is not subject to the selection rules governing the emission of x-radiation, additional information can be obtained from the Auger electron energy distribution.

Excitation of Auger peaks by a beam of low velocity electrons provides an interesting technique for surface analysis.

"Plasma" peaks of the type reported by Ruthemann, and interpreted by Pines and Bohm, were also observed.

• Received 5 June 1953

DOI:https://doi.org/10.1103/PhysRev.91.1382