Photoelectron spectroscopy and photochemistry of tetracyanoethylene radical anion in the gas phase

A combined photoelectron spectroscopy, photofragmentation and clustering study of the tetracyanoethylene (TCNE) radical anion in the gas phase is reported. The adiabatic electron affinity of TCNE is 3.16(2) eV. This result represents an order-of-magnitude improvement in the uncertainty over the presently accepted, indirectly determined value. The photodissociation of the anion at 355 and 266 nm leads to three anionic channels: one yielding CN ^- and the other two corresponding to the loss of one or two CN groups from the parent anion. The CN ^- fragment channel is dominant at 355 nm, while the double-dissociation channel dominates 266 nm photochemistry.