Experimental investigation of radiative lifetimes of vibrational levels at the electronic ground state of C2−

Abstract

Radiative lifetimes of the vibrational levels v=2 to v=4 of the X 2Σg+ ground state of the C2− molecular ion have been experimentally investigated by photodetachment in a storage ring. The lifetime of the v=3 level was 0.32±0.02 s for 12C12C−, and 0.22±0.02 s for 12C13C−. For both ions, the lower limit for the v=2 lifetime was 5 s, and the upper limit for the v=4 level was ∼100 ms. The measured lifetime for v=3 of 12C12C− is a factor of 4 smaller than found in a calculation [P. Rosmus and H. Werner, J. Chem. Phys. 80, 5085 (1984)]. The results point to the existence of at least one bound vibrational level of the lowest 4Σu+ state.