Spark Spectrum of Copper (Cu II)

Abstract

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 $^{3}P$, $^{3}D^{\ensuremath{'}}$, $^{3}F$, $^{1}P$, $^{1}D^{\ensuremath{'}}$, $^{1}F({d}^{9}p)$; (3) a high set $^{3}D$, $^{1}D({d}^{9}, s)$; (4) probably a $^{1}S({d}^{10})$, 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 ${^{3}D_{3}}^{\ensuremath{'}}$ 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 $\ensuremath{\lambda}1944$.Comparison with corresponding terms in Ni(I) and Pd (I).---A comparison is made with corresponding terms in Ni(I) and Pd(I) and it is shown that the limits of the component term series in all three cases apparently do not agree with Hund's predictions. It is important that the difference $^{3}D_{3}\ensuremath{-}^{3}D_{1}$ in the three spectra is constant within the series to less than $\frac{1}{10}%$; in the case of Cu(II), being apparently absolutely constant and equal to the difference $^{4}D_{4}\ensuremath{-}^{4}D_{1}$ of the arc spectrum.An ionization potential for Cu(II) is calculated as about 20.5 volts.