Almeida, D.; Antunes, R.; Garcia, G.; McCullough, R. W.; Eden, S. and Limão-Vieira, P.
(2012).
Mass spectrometry of anions and cations produced in 1-4 keV H-, O-, and OH- collisions with nitromethane, water, ethanol, and methanol.
International Journal of Mass Spectrometry, 311
pp. 7–16.
(
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Abstract
Interactions between 1 and 4 keV anions (H−, O−, and OH−) and gas-phase molecules (nitromethane, water, ethanol, and methanol) have been studied using quadrupole mass spectrometry of the product anions and cations. The low collision velocities (0.07–0.40 vBohr) provide favourable conditions for electron transfer from the anion projectile to the neutral target molecule yielding negative ion formation, while strong competition with cation formation is also observed. Relative production of fragment cations increases with H− impact energy and with projectile mass when energy is constant. Considered together, these results suggest a momentum dependence on collisional energy deposition. As far as negative ion production is concerned, comparisons with previous free electron attachment studies are drawn as a starting point for the interpretation of the anion fragmentation channels. For nitromethane and water, the present anion fragmentation patterns are substantially different to the free electron attachment data. Conversely the fragmentation channels of ethanol and methanol anions only show clear dependence on the electron attachment/transfer process in terms of the relative anion yields.
| Item Type: |
Journal Article
|
| Copyright Holders: |
2012 Elsevier B. V. |
| ISSN: |
1387-3806 |
| Funders: |
ITS-LEIF network, Portuguese Foundation for Science and Technology (FCT-MCTES), British Council Treaty of Windsor Programme, EPSRC Life Sciences Interface Fellowship, Marie Curie Intra-European Reintegration Grant |
| Keywords: |
negative and positive ion formation; dipole-bound state |
| Academic Unit/Department: |
Science > Physical Sciences |
| Interdisciplinary Research Centre: |
Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR) |
| Item ID: |
31683 |
| Depositing User: |
Sam Eden
|
| Date Deposited: |
30 Jan 2012 17:56 |
| Last Modified: |
22 Nov 2012 17:16 |
| URI: |
http://oro.open.ac.uk/id/eprint/31683 |
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