Transient negative ion

J. C. Y. Chen, Theory of Transient Negative Ions of Simple Molecules, in Advances in Radiation Chemistry, edited by M. Burton and J. L. Magee, Wiley, New York, 1968, Volume I. 

Electrons in liquid nitrogen, liquid oxygen, and liquid carbon monoxide exhibit ionic mobilities of the order of 10" cm V S" which are thermally activated (Loveland et al., 1972). In liquid nitrogen, an increase of the electron mobility with field strength was observed above 60 kV/cm (Sakai et al., 1983). Gee et al. (1985) proposed the existence of transient negative ions, while Sakai et al. (1993) assume localization of the electron in a bubble. 

From the above discussion we see that electron-molecule interactions can lead to transient negative ion (TNI) formation and subsequently to a variety of chemical changes. On TNI formation, an extra electron is captured into the unoccupied molecular orbital (UMO) of the neutral molecule, and a shape or core-excited resonance results (see O Fig. 34-4). 

Schematic diagram showing the electronic configuration of a neutral (a) and transient negative ion (TNI) (b, c). The interacting electron initially captures into the unoccupied MOs of the neutral molecule resulting in TNI formation via (a) shape resonance or (c) core-excited resonance. For a shape resonance, the electron can interact with any unoccupied MO. The SOMO was the empty LUMO before the LEE interaction. In core-excited resonance, on electron interaction an electronic transition takes place from an inner shell to the vacant MOs creating a "hole"(-i- charge) in the inner shell, shown by an arrow (c). The up and down arrows show the occupancy of the molecular orbitals (MOs) with electrons of ocand 3 spins. HOMO highest occupied molecular orbital, LUMO lowest unoccupied molecular orbital, SOMO singly occupied molecular orbital...

Vertical excitation energies (AE, eV) of transient negative ion (TNI) of DNA/RNA bases calculated using TD-BSLYP/fr-SIG and TD-BHandHLYP/6-31G methods and their comparison with available experimental values ... 

A transient negative ion state that is dissociative in the Franck-Condon region of the neutral species. 

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