Double Electron Ejection in the Photoabsorption Process

Electrons ejected from neon by Mg K_ and Al K_ x rays and from argon by Ti K_ x rays have been studied with an electrostatic energy analyzer. On the low-energy side of the photolines characteristic of single electron emission, discrete peaks and continua are observed which respectively indicate excitation and ionization of a second electron. From these electron spectra, the following probabilities of two-electron transitions are derived (per photoabsorption event): Ne KL: (18. 51. 0) %; Ar KL: (2. 50. 8) %; and Ar KM: (20. 71. 4) %. In about 85% of the double events, both electrons go into the continuum; in about 15%, the less tightly bound electron is promoted to excited discrete states. With the use of single-electron Hartree-Fock wave functions, the theory of electron shakeoff accounts for the observed intensities. The shape of the continuum electron spectra is in fair agreement with theoretical predictions. About 80% of the shakeoff electrons have energies of 0E₈, where E₈ is the binding energy of the L or M electron in an atom that lacks one K electron. Consequences of the present study in regard to x-ray and Auger-electron satellites are discussed, and it is found that specific satellites can be associated with specific double-hole configurations. The following relative intensities of K_ satellites were measured for Mg, Al, and Ti: 13%, 8. 5%, and 4%, respectively.