The Arc Spectrum of Copper

Abstract

The arc spectrum of coppper is partly an ordinary doublet spectrum with lowest term $^{2}S=62308.0$; and partly a complicated spectrum with lowest term $m^{2}D_{3}=51105.5$ and $m^{2}D_{2}=49062.6$. The next lowest terms of the complicated spectrum are $^{4}P$, $^{4}F$, $^{4}D^{\ensuremath{'}}$, $^{2}F$, $^{2}P$, $^{2}D^{\ensuremath{'}}$ in the order given extending from $^{4}P_{3}=23289.4$ to ${^{2}D^{\ensuremath{'}}}_{3}=15709.7$. They combine with $^{2}S$ and $m^{2}D$. The quartets are all inverted, while the doublets are not. There are eleven higher terms which include amongst others a second set $^{2}F$, $^{2}P$, $^{2}D^{\ensuremath{'}}$. This is all as predicted by the Heisenburg-Hund theory. Most of the lines of the arc spectrum are due to the combinations of the above quartets and doublets with a set of terms having negative wave-numbers extending from -95.2 to -14772.4. In particular, the lowest four negative terms are a complete $^{4}D$ and form by combination with $^{4}P$, $^{4}F$, $^{4}D^{\ensuremath{'}}$ multiplets of great intensity in the visible. The other negative terms include a set $^{4}S$, $^{4}P^{\ensuremath{'}}$, $^{4}D$, $^{4}F^{\ensuremath{'}}$, $^{4}G$, which also combine with considerable intensity with the first mentioned quartets. The limit of the negative quartet terms can be calculated to be at roughly -22,000. This should be the lowest spark $^{3}D$ term.The nature of the quartet spectrum was partly determined from Zeeman effects in the ultra-violet below 2500. The $g$-values of many of the terms are irregular but the $g$-sums are correct. Line intensities were used mainly as criteria for the designation of terms. Unresolved Zeeman effects give confirmation in many cases.The two types of spectra are connected by combinations of the lowest terms of each with higher terms of the other. Other theoretically possible combinations do not occur.