A surface detector for metastable atoms

A surface detector for the detection of metal atoms in metastable states is ; described. The surface used for de-excitation of the metastable atoms is produced fi om the condensed vapour of the target metal. The resulting seco ndary-electron emission is detected by a channel electron multiplier. The d esign offers the important advantage of a low work function and high select ivity for the secondary electrons. Efficient cooling of the detection surfa ce and the electron multiplier makes it possible to use the detector in stu dies of metal vapours at temperatures of up to 400 degrees C. An example of the: use of the detector to measure the electron-impact excitation functio n for inner-shell excited metastable states in potassium is presented.