Two-Electron-Impact Excitation of Calcium, Strontium, and Barium Atoms

We have measured the energy dependences that govern the cross sections for Minsk, electron-impact excitation of spectral transitions from the levels of alkali-earth atoms that correspond to a simultaneous excitation of s ²-valent electrons. Measurements were performed on a setup with intersecting beams of atoms and electrons. The energy dependences for two- and one-electron excitations are compared. It is found that the energy dependences for the spectral transitions from one- and two-electron excitation levels that have the same orbital quantum numbers are similar.