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

With an electrodeless discharge in caesium vapor as a light source, the spark spectrum of caesium has been completely rephotographed in the region λ2300-λ10,000 in the first order of 21 ft. concave grating and with a Hilger E1 quartz spectrograph. The observations of Sommer in the region λ3268-λ7280 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 5p⁵²P11/2 limit were identified. In the present work most of the terms of the 5p⁵ (²P1/2) $5d$, $6d$, $6s$, $7s$, and $6p$ configurations were located as well as a few new terms belonging to the 5p⁵²P11/2 limit, and about 100 additional lines were classified in the Cs II spectrum.