Spark Spectrum of Copper (Cu II)

Terms in the spectrum of Cu(II.).—The spark spectrum of copper consists of (1) a low set of terms ${}_{}{}^3{}_{}{}^{}D$ and ${}_{}{}^1{}_{}{}^{}D$ from the structure ($d^{9}s$); (2) an intermediate set ${}_{}{}^3{}_{}{}^{}P$, ${}_{}{}^3{}_{}{}^{}D_{}^{\prime }{}_{}{}^{}$, ${}_{}{}^3{}_{}{}^{}F$, ${}_{}{}^1{}_{}{}^{}P$, ${}_{}{}^1{}_{}{}^{}D_{}^{\prime }{}_{}{}^{}$, ${}_{}{}^1{}_{}{}^{}F\left(d^{9}p\right)$; (3) a high set ${}_{}{}^3{}_{}{}^{}D$, ${}_{}{}^1{}_{}{}^{}D(d^9, s)$; (4) probably a ${}_{}{}^1{}_{}{}^{}S\left(d^{10}\right)$, the lowest term and giving combinations outside the observed range. All of these terms except ${}_{}{}^1{}_{}{}^{}S$ have been identified by intensities of combinations and by Zeeman effects. They are all inverted except ${}_{}{}^3{}_{}{}^{}F$ which is only partially so; and the interval rule does not hold. The terms ${{}_{}{}^3{}_{}{}^{}D_3^{}{}_{}{}^{}}^{\prime }$ and ${}_{}{}^1{}_{}{}^{}F_3^{}{}_{}{}^{}$ apparently share their $g$-sum and are otherwise not differentiable. The value of ${}_{}{}^1{}_{}{}^{}S$ can be found from arc spectrum limits to be about 22224 wave numbers lower than ${}_{}{}^3{}_{}{}^{}D_3^{}{}_{}{}^{}$. The application of the combination principle makes possible the calculation of accurate wave numbers in the ultra-violet to $\lambda 1944$.