Series Spectra of Two-Valence-Electron Atoms of Boron (BII) and Carbon (CIII)

Series spectra of ${\mathrm{B}}_{\mathrm{II}}$ and ${\mathrm{C}}_{\mathrm{III}}$.—By methods previously reported in the identification of lines in the extreme ultraviolet, 13 lines in addition to the $p{p}^{\prime }$. group of ${\mathrm{B}}_{\mathrm{II}}$ have been identified, completing the classification of all lines known to be due to ${\mathrm{B}}_{\mathrm{II}}$. Taking the $4f$ level as 27800 (probably correct to within 200 frequency units), the following term values were obtained for ${\mathrm{B}}_{\mathrm{II}}$: $3s$, 72930.8; $4s$, 36655.5; $2p_1$, 165343.9; $2p_{2,3}$, 165362.7; $3p_1$, 59006.5; $3p_{2,3}$, 59010.0; $3d$, 52054.2; $4d$, 28640.4; $5f$, 17795.7; $2S$, 194325.9; $3S$, 66665.1; $2P$, 120929.4; $3D$, 48410.3. In the case of ${\mathrm{C}}_{\mathrm{III}}$, 8 lines in addition to the $p{p}^{\prime }$ group were identified, and taking the $4f$ level as 62600, the following term values were obtained for ${\mathrm{C}}_{\mathrm{III}}$: $3s$, 146197.2; $2p$, 331939.2; $3p_1$, 124685.8; $3p_2$, 124698.6; $3p_3$, 124704.1; $3d$, 114387.2; $2S$, 375463.1; $2P$, 273111.0.