Photoionization spectrum of theP3ground state of neutral carbon

The atomic absorption of C i has been studied in the 1100-385-Å spectral region, using the flash-pyrolysis method to produce the absorbing layer and a BRV as a continum source. Thirty-four lines belonging to the $2s^{2}2p^2{}_{}{}^3{}_{}{}^{}P-2s2\mathrm{}{p}^2\mathrm{np}{}_{}{}^3{}_{}{}^{}D_{}^o{}_{}{}^{}$ series converging to the $2s2p^2{}_{}{}^4{}_{}{}^{}P$ ionization limit have been observed and for the first time resolved in fine structure. In addition, energies of $\mathrm{np}{}_{}{}^3{}_{}{}^{}D_{1,2,3}^o{}_{}{}^{}$ are deduced from these observed lines. Three new lines have been observed and identified as simultaneous excitation of the two outer electrons to the final state $2s^{2}3pnd{}_{}{}^3{}_{}{}^{}D_{}^o{}_{}{}^{}$. The relative photoionization cross section of the ground state ${}_{}{}^3{}_{}{}^{}P$, as measured in the same range of wavelengths, is found to be consistent with theoretical predictions.