Tetracyanoethylene, its ions and ionic fragments

The Fourier-transform infrared spectra of tetracyanoethylene cation, C6N4+, and several of it fragment ions: CNC+, C4N2+, C3N2+, C5N3+, and C6N3+, in solid neon are obtained via mass-selective deposition. The ions are formed via electron-impact ionization of tetracyanoethylene, mass-selected in a quadrupole mass filter and deposited together with an excess of electrons to prevent a buildup of space charge. Upon irradiation of these matrices with a tungsten lamp, electrons are mobilized and attach to electron-deficient dopants; not only neutralizing the small amount of cations in the matrix, but also forming the well-known tetracyanoethylene anion, C6N4-. For each molecular ion, the new infrared assignments are supported by density functional calculations.