Radioactive Isotope of Gold,Au19879* and Low Energy Range of Its Spectrum

Abstract

The soft range of the energy spectrum of $_{79}\mathrm{Au}^{198}$ was measured by means of a magnetic lens $\ensuremath{\beta}$-ray spectrometer. The part of the spectrogram so obtained shows a part of continuous $\ensuremath{\beta}$-spectrum and a broad line spectrum of secondary $\ensuremath{\beta}$-rays ejected from the $L$-level of gold by the softest component of non-corpuscular radiation first found by Richardson. The peak of the line spectrum at ${H}_{\ensuremath{\rho}}=837.5$ corresponds to the maximum energy of 58.4 kev of electrons ejected from $L$-group of gold. The energy of the radiation which might have given rise to these $\ensuremath{\beta}$-rays must be 70.3 kev with a wave-length $\ensuremath{\lambda}=175.7$ x.u. This value of $\ensuremath{\lambda}$ is practically identical with the estimated value of the wave-length of $K{\ensuremath{\alpha}}_{1}$ line of mercury. The breadth and the spread of the line towards the low energy side indicate that the spectrum of the $L$-group of electrons of gold, ejected by a 70.3-kev energy radiation partly overlaps another line spectrum of the same group of electrons ejected by a radiation, softer than 70.3 kev radiation by an energy of the order of only a few kev. This softer one could be identical with the $K$-radiation of $_{78}\mathrm{Pt}^{198}$. The softest component of non-corpuscular radiation found in $_{79}\mathrm{Au}^{198}$ is therefore very likely composed of the $K$-radiation of $_{78}\mathrm{Pt}^{198}$, and the $K$-radiation of $_{80}\mathrm{Hg}^{198}$. From the evidence, the radioactive isotope of gold $_{79}\mathrm{Au}^{198}$ appears to have a dual transition, a transition to $_{80}\mathrm{Hg}^{198}$ following $\ensuremath{\beta}$-decay and another to $_{78}\mathrm{Pt}^{198}$, following $K$-capture as assumed by Sizoo and Eijkman.