Dissociative electron attachment to CO and NO:: the O- production threshold revisited

Dissociative electron attachment (DA) to CO and NO has been investigated with a new crossed beams apparatus using a hemispherical electron monochromator. The DA cross-section curve for CO shows a vertical onset at the threshold (9.63 eV) of the lowest possible DA channel O-(P-2) + C(P-3). It is also possible to see a distinct onset (and peak) at the thermochemical threshold for the first excited channel O-(P-2)S + C*(D-1). The DA cross-section curve for NO previous exhibits a vertical onset at the threshold (7.47 eV) for the first excited DA channel O-(2P) + N *(D-2) and below 7.47 eV no signal for the energetically lower ground-state channel O-(P-2)+ N(S-4) with a thermochemical threshold of 5.07 eV. We observe above similar to 8.5 eV the occurrence of anions associated with the second excited DA channel O-(P-2)+ N*(P-2). (C) 1998 Elsevier Science B.V. All rights reserved.