Formation of NO- following electron attachment to NO clusters

Low-energy (0-1 eV) electron attachment to NO clusters is studied with high-energy resolution (15 meV, FWHM). The dominant signal is NO- which has not been observed in previous Rydberg electron transfer studies to NO clusters. The relative cross-section for NO- formation shows a sharp peak close to 0 eV and a series of further weak peaks with a spacing of about 190 meV, The '0 eV' peak is ascribed to 's-wave capture' by the entire target cluster. Due to the low adiabatic electron affinity of NO (26 meV), NO- cannot be the result of an evaporative attachment reaction. It is suggested that neutral products like N-2, via the strongly bound (ONNO)(-) intermediate, are involved. The weak structures are tentatively assigned as arising from transitions to vibrational excited states of solvated NO-. (C) 1998 Elsevier Science B.V. All rights reserved.