An Extension of the Spark Spectrum of Copper, Cu II

Abstract

The ground term of Cu II is a $3d^{10}{}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$. The next higher terms are $3d^{9}4s{}_{}{}^1{}_{}{}^{}D{}_{}{}^3{}_{}{}^{}D$ and still higher are found the terms $3d^{9}4p{}_{}{}^1{}_{}{}^{}\left(P^{\circ }{D}^{\circ }{F}^{\circ }\right){}_{}{}^3{}_{}{}^{}\left(P^{\circ }{D}^{\circ }{F}^{\circ }\right)$. These facts were already known from the work of other investigators. With a Schüler lamp of the hollow cathode type as a source, the spectrum of copper was photographed by means of a vacuum spectrograph which was so designed that the region 0A—2600A could be photographed on one plate. Two higher members of the $3d^9\mathrm{ns}{}_{}{}^1{}_{}{}^{}D{}_{}{}^3{}_{}{}^{}D$ series have been found, thus giving in all four members of both series, from which the limits of the series have been calculated. The calculations show that the $3d^{10}{}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$ level lies 163, 634.2 ${\mathrm{cm}}^{-1\mathrm{}}$ below the $3d^9{}_{}{}^2{}_{}{}^{}D_{\frac{5}{2}}^{}{}_{}{}^{}$ of Cu III from which the ionization potential of Cu II is computed to be 20.2 volts. This places the first members of the $3d^9\mathrm{ns}{}_{}{}^3{}_{}{}^{}D_{3,2,1}^{}{}_{}{}^{}$ series at 141,709.2 ${\mathrm{cm}}^{-1\mathrm{}}$, 140,790.7 ${\mathrm{cm}}^{-1\mathrm{}}$ and 139,639.5 ${\mathrm{cm}}^{-1\mathrm{}}$ respectively. Higher members of the $3d^9\mathrm{np}{}_{}{}^1{}_{}{}^{}\left(P^{\circ }{D}^{\circ }{F}^{\circ }\right){}_{}{}^3{}_{}{}^{}\left(P^{\circ }{D}^{\circ }{F}^{\circ }\right)$ series have also been identified, thus making it possible to confirm Hund's predictions concerning the limits which the various series members approach.