Revision of the ionization energy of neutral carbon

This publication describes a re-analysis of previously published data on neutral carbon (C I). We used critically examined and improved values for the line energies of the absorption spectrum of molecular iodine to calibrate the transition energies of C I absorption lines originating from the 1s22s22p3s 3P°2 level and terminating on highly excited Rydberg states of the 1s22s22pnp 3D3 series. This series converges on the first excited fine-structure level of the ionic ground configuration. Additional use of improved energy values for the 1s22s22p3s 3P°2 level and for the fine-structure interval of the ionic ground state together with modern fitting techniques lead to a new value of the ionization energy of neutral carbon with 9 times the precision of previous work, 90 820.348(9) cm−1 (equivalent to 11.260 2880(11) eV), as well as a table of predicted values for the energies of unobserved states in the series.