Photoionization of C4 molecular beam: Ab initio calculations

Hochlaf, Majdi; Nicolas, Christophe; Poisson, Lionel
July 2007
Journal of Chemical Physics;7/7/2007, Vol. 127 Issue 1, p014310
Academic Journal
Large computations are performed on the C4+ cation in order to characterize its stable isomers and its lowest electronic excited states using configuration interaction methods and large basis sets. Several stable isomers are found including a linear C4+(l-C4+), a rhombic C4+(r-C4+) (or cyclic), and a branched (d-C4+) structure. Our calculations show a high density of electronic states for all of these isomers favoring their interactions. By combining the present ab initio data and those on neutral C4, the l-C4(X)+hν→l-C4+(X+)+e-, d-C4(X)+hν→d-C4+(X+)+e-, and r-C4(X)+hν→r-C4+(X+)+e- vertical photoionization transition energies are computed at 10.87, 10.92, and 10.77 eV, respectively. Photoionizing a C4 molecular beam results on an onset at 10.4–10.5 eV and then to a linear increase of the signal due to the opening of several ionization channels involving most of the C4 and C4+ isomers and electronic states.


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