Tunneling electron loss from isolated platinum tetrahalide dianions

Electron detachment from doubly charged anions PtClxBr4-x2- to form PtClxBr 4-x- (x=0-4) was probed for in a Fourier-transform ion-cyclotron-resonance mass spectrometer at 288 K. The corresponding decay rates were measured as a function of collision gas pressure. In the zero-pressure limit, nonzero u nimolecular decay rate constants were observed for x=4 and 3 (0.273 +/-0.03 5 and 0.056 +/-0.019 s(-1) for 288 K, respectively). These show a strong te mperature dependence suggesting the new phenomenon of blackbody radiation i nduced tunneling electron loss. Comparison to electron tunneling rates calc ulated by means of the Wentzel-Kramers-Brillouin approximation using Coulom b barrier properties and electron detachment energies derived from ab initi o quantum chemical calculations provides a qualitative rationalization of t he observed trends. (C) 2001 American Institute of Physics.