Lifetime of a K-shell vacancy in atomic carbon created by 1s→2p photoexcitation of C+

Lifetimes for K-shell vacancy states in atomic carbon have been determined by measurement of the natural linewidth of the 1s --> 2p photoexcited states of C+ ions. The K-shell vacancy states produced by photoionization of atomic carbon are identical to those produced by 1s --> 2p photoexcitation of a C+ ion: 1s2S(2) 2p(2) D-2, P-2, and S-2 autoionizing states occur in both cases. These vacancy states stabilize by emission of an electron to produce C2+ ions. Measurements are reported for the lifetime of the 1s2s(2) 2p(2) D-2, P-2 and S-2 autoionizing states of C+: 6.3 +/- 0.9 fs, 11.2 +/- 1.1 fs and 5.9 +/- 1.3 fs respectively. Knowledge of such lifetimes is important for comparative studies of the lifetimes of K-shell vacancies in carbon-containing molecules, benchmarking theory, and interpreting satellite x-ray spectra from astrophysical sources such as x-ray binaries. Absolute cross sections were measured for both ground-state and metastable-state ions providing a stringent test of state-of-the-art theoretical calculations.