Anregung gebundener Atomzustände durch die plötzliche Zentralfeldänderung beim β?-Zerfall des Kerns

By the sudden change of nuclear charge during β^?-decay the daughter-ion is ionized or excited with probabilities of the order of some percent; other processes in the electron shell may be neglected, therefore unperturbed excitations can be measured by detecting photons emitted from the decaying excited atomic states in delayed coincidence with β^?-particles as is shown in an earlier paper for the Kr 85-β^?-decay. More extensive measurements of the photonemission after this decay give results in good agreement with theoretical predictions. Mostly such photons are observed, which can be emitted after a monopol-excitation, for which the selectionrulesΔ J=0 andΔ l=0 are valid. The total excitationprobability into both 5p(J=0)-states of Rb II is found to be P(4p?5p)=5,6±1,0%. The lifetimes of these two states are measured (correspondingly) to be τ=7,6 ±0,5 nsec, from which the reduced matrixelements ¦〈5p∥D∥5s〉¦²=18,9±3,2 and ¦〈5p∥D∥4d〉¦²=10,4 ±1,8 a.u. are calculated.