High-resolution ejected-electron spectra of K I and K II autoionising levels excited by low-energy electron impact on potassium vapour

The ejected-electron spectrum of potassium vapour has been observed at 50 degrees and 75 degrees with respect to an incident-electron beam of 30 to 400 eV incident energy. Ejected-electron energies are in the range 4 to 21.5 eV. A total of 84 autoionising states of K I are reported, of which 49 have been identified by comparison with ultraviolet absorption data. Some of the remaining levels are assigned tentatively using available theoretical data. In addition, three states belonging to the K II autoionisation spectrum are identified.