Extension of the First Spark Spectrum of Caesium (Cs II)

Abstract

With an electrodeless discharge in caesium vapor as a light source, the spark spectrum of caesium has been completely rephotographed in the region $\lambda 2300-\lambda 10,000$ in the first order of 21 ft. concave grating and with a Hilger E1 quartz spectrograph. The observations of Sommer in the region $\lambda 3268-\lambda 7280$ were confirmed and extended and many new lines were photographed outside Sommer's range. These data were used to extend the classifications of Laporte, Miller and Sawyer, based on Sommer's data supplemented by vacuum spectrograph measurements, in which practically only terms belonging to the $5p^5{}_{}{}^2{}_{}{}^{}P_{1\frac{1}{2}}^{}{}_{}{}^{}$ limit were identified. In the present work most of the terms of the $5p^5 \left({}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{}\right)$ $5d$, $6d$, $6s$, $7s$, and $6p$ configurations were located as well as a few new terms belonging to the $5p^5{}_{}{}^2{}_{}{}^{}P_{1\frac{1}{2}}^{}{}_{}{}^{}$ limit, and about 100 additional lines were classified in the Cs II spectrum.