| Abstract
| - In a kinematically complete experiment on the dissociative double ionization of CO2 by electron impact,spontaneous and metastable decay have been observed via the channel C→ CO+ + O+. The metastabledecay shows a lifetime of 5.8 ± 1.5 μs. The measured kinetic energy release spectrum of the dissociationshows one broad peak. To understand the observed features, ab initio potential energy surface (PES) for theground electronic state of Cwas computed using a multireference configuration interaction method anda correlation-consistent polarized-valence quadruple-ζ basis set, for a range of internuclear distances andO−C−O bond angles, and an analytic fit of the PES was obtained. The computed PES clearly indicates themetastability of the dication and yields a barrier height and an asymptotic limit in fair agreement with thereported data. A time-dependent quantum mechanical approach was used to compute the ground vibrationalstate wave function of CO2 in its ground electronic state. Assuming a Franck−Condon transition, the samefunction was taken to be the initial wave function at time t = 0 for the time evolution on the fitted PES forthe ground electronic state of C. The autocorrelation function was computed and Fourier transformed toobtain the excitation spectrum. Upon convolution with the instrument resolution function, the kinetic energyrelease spectrum was obtained, in good agreement with the experimental results, particularly at lower energies.The discrepancies at higher energies are attributed to the noninclusion of the excited states of Cin thedynamical study.
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