Die Anregung des Tochterions Rb+ durch die plötzliche Kernladungsänderung von85Kr,eingebaut in feste Edelgase

By the sudden change of nuclear charge the daughter-ion is excited with a propability of some percent (monopole-excitation). When⁸⁵Kr is trapped in various solids of rare gases, the daughter-ion Rb⁺ acts as a probe: The spectra of emitted photons contain information about the influence of the surrounding solid on the levels of the excited Rb⁺. These spectra have been observed in delayed coincidence with the nuclear process (β-decay); direct excitation by charged particles is excluded. The results are closely connected to the behaviour of the decaying atom in free state and solid krypton: There are narrow bands (the daughter-ion occupies a regular lattice site) and blue-shifted (Δ v) broad bands (emission from daughter-ion displaced to interstitial sites by recoil).Δ v is different in the various solids of rare gases and increases from Ar to Xe; this is due to the various polarizabilities and lattice constants. A theoretical estimate fits well the experimental values. Besides, the experimental results show that the excitation-probability for⁸⁵Kr in Kr is greater than for⁸⁵Kr in Ar or Xe, which also agrees with theoretical estimates. Furthermore, information about the displacement energies of the Rb⁺ in the various solids of rare gases are gained from the ratio of intensities of the narrow bands to that of the broad bands, which are compared to displacement energies gained from rare-gas pair potentials.