Internal Conversion, Multipole Mixing, and Auger Spectrum inZn67fromGa67Decay

Absolute internal-conversion coefficients measured with high electron resolution and with a Ge(Li) spectrometer have been studied in seven transitions in ${\mathrm{Zn}}^{67}$ from 78-h ${\mathrm{Ga}}^{67}$ decay. From these and from $L$ subshell ratios for the three lowest energy transitions, we deduce the following multipolarities: 93 keV, pure $E2;184\mathrm{} \mathrm{keV},M1+(8-12\% E2)$; all others predominantly $M1\mathrm{}$, with $E2\mathrm{}$ required in the 91- and 494-keV transitions. The retardation factor of the $l$-allowed 91-keV transition is 500, which is larger than that (340) for the $l$-forbidden 184-keV transition ($E2\mathrm{}$-component enhancement of 17) originating at the same level. Conversion data, together with a reanalysis of $\gamma -\gamma$ angular-correlation measurements of Rietjens and Van den Bold, lead unambiguously to the following level spin assignments, in agreement with those from ($d,p$) stripping and Coulomb excitation: ($\mathrm{keV},J\pi$); ground state $\frac{5}{2}-$; 93.317±0.02, ½—; $184.595\pm 0.04,\frac{3}{2}-;393.59\mathrm{}\pm 0.04,\frac{3}{2}-;887.87\mathrm{}\pm 0.1,\frac{3}{2}-$. Conversion coefficients show somewhat better agreement with those calculated by Sliv and Band (extrapolated from $Z=33\mathrm{}$) than with those of Rose for the $L$ shell, but indicate that both computations give $L$-shell coefficients too small (∼10% for Sliv and Band, ∼20% for Rose) for this $Z$ range. The empirical $Z$ displacement rule for $M_I$ conversion due to Chu and Perlman ($\Delta Z=-7.0\mathrm{}$), which, applied to the unscreened, point-nucleus $M$ conversion values of Rose gives agreement for all energies and multipolarities above $Z=50\mathrm{}$, is found to require $\Delta Z=-9.5\mathrm{}$ for agreement at $Z=30\mathrm{}$. Six of nine predicted lines in the KLL Auger spectrum of Zn are resolved; energies determined are 7-13 eV above those calculated by Hörnfeldt, and intensities agree with recent experimental results at $Z=32\mathrm{}$ except for the $K-L_1{L}_3\left({}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}\right)$ line, where our intensity is lower by a factor of 2.