LOW-ENERGY-ELECTRON ATTACHMENT TO CLUSTERS OF NITRIC-OXIDE

The attachment of low energy (9-80 meV) electrons to clusters of nitri c oxide (NO) has been studied by means of Rydberg electron transfer (R ET) from selected nd states of rubidium (n = 15-40). The product negat ive ions have stoichiometry (NO)(x)(-) (x = 2-60) and exhibit even/odd intensity alternations (odd > even) which increase in magnitude with cluster size such that only odd cluster ions are observed for x greate r than or similar to 20. The experimental data are consistent with an evaporative attachment mechanism in which the production of odd cluste r ions is kinetically favored due to differences in stabilities betwee n odd and even cluster ions. These differences in stabilities are attr ibuted to the spin pairing of valence electrons which results in exten sive dimerization of NO in condensed phases. It is postulated that, fo r x > 3, the excess electron becomes localized to form an (NO)(3)(-) i on which is solvated by NO dimers. Interaction potentials governing th e initial electron capture process are also discussed.