Energy and angular dependence of H-(D-) ions produced by dissociative electron attachment to H2O(D2O)

Belić, D.; Landau, M.; Hall, Richard

doi:10.1088/0022-3700/14/1/017

Cited by 81 publications

(99 citation statements)

References 21 publications

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“…We calculate that the two-body cross sections for both OH (X 2 Π) and OH ( 2 Σ) are dominated by diatoms in low-energy rovibronic states with high kinetic energy release. In this respect we confirm the results of Belic, Landau, and Hall [8], shown in the inset of Fig. 2b.…”

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confidence: 90%

“…is a resonant process that involves the capture of a free electron into a transient negative ion state which subsequently dissociates to produce neutral and ionic fragments. Previous experimental [1][2][3][4][5][6][7][8][9][10] and theoretical studies [11][12][13][14][15][16][17][18][19] [9] observed the opening of the lower three-body channel, as discerned through the kinetic energy distribution of the O − fragment. However, because of the large O atom/H 2 mass ratio, such a measurement is difficult and a quantitative experimental determination of the final-state branching ratios among the two-and three-body breakup channels has yet to be published.…”

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confidence: 99%

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Three-body breakup in dissociative electron attachment to the water molecule

2008

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We report the results of ab initio calculations on dissociative electron attachment (DEA) to water that demonstrate the importance of including three-body breakup in the dissociation dynamics. While three-body breakup is ubiquitous in the analogous process of dissociative recombination, its importance in low-energy dissociative electron attachment to a polyatomic target has not previously been quantified. Our calculations, along with our earlier studies of DEA into two-body channels, indicate that three-body breakup is a major component of the observed O − cross section. The local complex potential model provides a generally accurate picture of the experimentally observed features in this system, reproducing some quantitatively, others qualitatively, and one not at all.PACS numbers: 03.65. Nk, 34.80.Ht Dissociative electron attachment (DEA) to the water molecule, [9] observed the opening of the lower three-body channel, as discerned through the kinetic energy distribution of the O − fragment. However, because of the large O atom/H 2 mass ratio, such a measurement is difficult and a quantitative experimental determination of the final-state branching ratios among the two-and three-body breakup channels has yet to be published.There is strong reason to believe that three-body breakup is important for describing DEA leading to O − production. In particular, examination of the shape of the 2 A 1 surface suggests that three-body breakup may be the key to describing O − production via this resonance. The 2 A 1 (1 2 A ′ ) electronic surrface slopes downward toward linear H-O-H geometry and is dissociative along the OH bonds. It provides a path for symmetric dissociation of the OH bonds to produce O − + H + H, but also slopes downward toward the H − + OH asymptotes. Similarly, the 2 B 2 diabatic surface, which equals the 2 B 2 adiabatic surface for C 2v geometries, provides a path toward symmetric dissociation through the conical intersection with the 2 A 1 state. Symmetric dissociation of the 2 B 2 state from the equilibrium geometry of the neutral leads to the O − + H + H three-body asymptote.Our methodology is very similar to that used in our previous calculations, so we provide only a brief summary

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confidence: 90%

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confidence: 99%

Three-body breakup in dissociative electron attachment to the water molecule

2008

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“…Electron attachment to an isolated water molecule results in spontaneous dissociation to form predominantly H Ϫ with minor abundances of O Ϫ and OH Ϫ also observed [72]. With increasing incident electron energies, some internal vibration modes can be excited, but the majority of the dissociation energy is carried away by the fragments in the form of kinetic energy [73].…”

Section: Evidence For Nonergodic Dissociationmentioning

confidence: 92%

Nonergodicity in electron capture dissociation investigated using hydrated ion nanocalorimetry

Leib

Donald

Bush

et al. 2007

J. Am. Soc. Mass Spectrom.

118

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Hydrated divalent magnesium and calcium clusters are used as nanocalorimeters to measure the internal energy deposited into size-selected clusters upon capture of a thermally generated electron. The infrared radiation emitted from the cell and vacuum chamber surfaces as well as from the heated cathode results in some activation of these clusters, but this activation is minimal. No measurable excitation due to inelastic collisions occurs with the low-energy electrons used under these conditions. Two different dissociation pathways are observed for the divalent clusters that capture an electron: loss of water molecules (Pathway I) and loss of an H atom and water molecules (Pathway II). For Ca(H 2 O) n 2ϩ , Pathway I occurs exclusively for n Ն 30 whereas Pathway II occurs exclusively for n Յ 22 with a sharp transition in the branching ratio for these two processes that occurs for n Ϸ 24. The number of water molecules lost by both pathways increases with increasing cluster size reaching a broad maximum between n ϭ 23 and 32, and then decreases for larger clusters. From the number of water molecules that are lost from the reduced cluster, the average and maximum possible internal energy is determined to be ϳ4.4 and 5.2 eV, respectively, for Ca(. This value is approximately the same as the calculated ionization energies of M(H 2 O) n ϩ , M ϭ Mg and Ca, for large n indicating that the vast majority of the recombination energy is partitioned into internal modes of the ion and that the dissociation of these ions is statistical. For smaller clusters, estimates of the dissociation energies for the loss of H and of water molecules are obtained from theory. For Mg(H 2 O) n 2ϩ , n ϭ 4 -6, the average internal energy deposition is estimated to be 4.2-4.6 eV. The maximum possible energy deposited into the n ϭ 5 cluster is Ͻ7.1 eV, which is significantly less than the calculated recombination energy for this cluster. There does not appear to be a significant trend in the internal energy deposition with cluster size whereas the recombination energy is calculated to increase significantly for clusters with fewer than 10 water molecules. These, and other results, indicate that the dissociation of these smaller clusters is nonergodic. . The effectiveness of the bottom-up method for complex samples can be enhanced by using multidimensional separations. Clemmer and coworkers elegantly demonstrated that combining on-line liquid chromatography (LC) with ion mobility spectrometry and MS can greatly improve separations without increasing analysis times over LC/MS alone [2][3][4]. In contrast, the "top-down" approach to protein characterization has the advantage that de novo sequencing, including the identification and structural localization of labile posttranslational modifications, can be done directly on protein mixtures without proteolysis [5,6]. This top-down approach has greatly benefited from the development of electron capture dissociation (ECD), a method pioneered by McLafferty and coworkers [6][7][8][9]. In a typical ECD experim...

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“…Experimental studies of DEA of water include those of Melton [37], Belic et al [38] and Curtis et al [39] and more recently Harb et al [40]. A very recent theoretical work [41] employed the Complex Kohn variational and a similar approach to ours.…”

Section: Dissociative Electron Attachmentmentioning

confidence: 97%

Electron-molecule collisions at low and intermediate energies using the R-matrix method

Gorfinkiel

Fauré²,

Taioli

et al. 2005

Eur. Phys. J. D

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Abstract. We present the latest developments of the R-matrix method as applied to electron-molecule collisions. A variety of calculations for H £ O are presented including the study of rotational excitation and preliminary data for dissociative electron attachment. Results for the application of the recently developed molecular R-matrix with pseudostates (MRMPS) method to neutral and cationic targets are also included. This method is currently being applied to the study of collisions with anionic targets. PACS. PACS-key discribing text of that key -PACS-key discribing text of that key

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Energy and angular dependence of H^-(D^-) ions produced by dissociative electron attachment to H₂O(D₂O)

Cited by 81 publications

References 21 publications

Three-body breakup in dissociative electron attachment to the water molecule

Three-body breakup in dissociative electron attachment to the water molecule

Nonergodicity in electron capture dissociation investigated using hydrated ion nanocalorimetry

Electron-molecule collisions at low and intermediate energies using the R-matrix method

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