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Updated: Jul 19, 2026

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F−
Published on: July 27, 2018
Photodetachment and photofragmentation pathways in the [(CO2)2(H2O)m]- cluster anions
Luis Velarde1, Terefe Habteyes, Andrei Sanov
1Department of Chemistry, University of Arizona, Tucson, Arizona 85721-0041, USA.
Abstract:
The mass-selected [(CO(2))(2)(H(2)O)(m)](-) cluster anions are studied using a combination of photoelectron imaging and photofragment mass spectroscopy at 355 nm. Photoelectron imaging studies are carried out on the mass-selected parent cluster anions in the m=2-6 size range; photofragmentation results are presented for m=3-11. While the photoelectron images suggest possible coexistence of the CO(2) (-)(H(2)O)(m)CO(2) and (O(2)CCO(2))(-)(H(2)O)(m) parent cluster structures, particularly for m=2 and 3, only the CO(2) (-) based clusters are both required and sufficient to explain all fragmentation pathways for m>/=3. Three types of anionic photofragments are observed: CO(2) (-)(H(2)O)(k), O(-)(H(2)O)(k), and CO(3) (-)(H(2)O)(k), k=m, with their yields varying depending on the parent cluster size. Of these, only CO(2) (-)(H(2)O)(k) can potentially result from (O(2)CCO(2))(-)(H(2)O)(m) parent structures, although an alternative mechanism, involving the dissociation and recombination of the CO(2) (-) cluster core, is possible as well. The O(-)(H(2)O)(k) and CO(3) (-)(H(2)O)(k) channels are believed to be triggered by the dissociation of the CO(2) (-) cluster core. In the CO(3) (-)(H(2)O)(k) channel, seen only in the range of m=3-6, the CO(2) (-) core dissociation is followed by an intracluster association of nascent O(-) with the solvent CO(2). This channel's absence in larger clusters (m>6) is attributed to hindrance from the H(2)O molecules.
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