Singlet state energy levels of C2H2+4 by double charge transfer spectroscopy

Abstract

The double ionisation energies to lower singlet states of C2H2+4 have been measured using double charge transfer spectroscopy as 30.9, 34.3, 36.2, 38.8 and 42.8 eV. These measurements are compared with the differing results obtained in two previous double charge transfer spectroscopy investigations and with other existing data on the C2H2+4 dication. In particular, these results are compared with the double-ionisation energies and vertical-ionisation spectrum which were calculated in a previous theoretical investigation.