| 1. |
- Andersson, Patrik U, 1970, et al.
(författare)
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Isotope exchange and structural rearrangements in reactions between size-selected ionic water clusters, H3O+(H2O)n and NH4+(H2O)n, and D2O
- 2008
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Ingår i: Phys.Chem.Chem.Phys. - : Royal Society of Chemistry (RSC). ; 10, s. 6127-6134
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen/deuterium exchange in reactions of H3O+(H2O)n and NH4+(H2O)n (1 n 30) with D2O has been studied experimentally at center-of-mass collisions energies of 0.2 eV. For a given cluster size, the cross-sections for H3O+(H2O)n and NH4+(H2O)n are similar, indicating a structural resemblance and energetics of binding. For protonated pure water clusters, H3O+(H2O)n, reacting with D2O the main H/D exchange mechanism is found to be proton catalyzed. In addition the H/D scrambling becomes close to statistically randomized for the larger clusters. For NH4+(H2O)n clusters reacting with D2O, the main mechanism is a D2O/H2O swap reaction. The lifetimes of H3O+(H2O)n clusters have been estimated using RRKM theory and a plateau in lifetime vs. cluster size is found already at n = 10.
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| 2. |
- Andersson, Patrik U, 1970, et al.
(författare)
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Ultra-dense deuterium: A possible nuclear fuel for inertial confinement fusion (ICF)
- 2009
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Ingår i: Physics Letters A. ; 373, s. 3067-3070
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Tidskriftsartikel (refereegranskat)abstract
- The ejection of deuterons with kinetic energy release (KER) of 630 eV was proved recently by measuring the laser-induced ion time-of-flight (TOF-MS) with two different detectors at different distances [S. Badiei, P.U. Andersson, L. Holmlid, Int. J. Mass Spectrom. 282 (2009) 70]. Realizing that the only possible energy release mechanism is Coulomb explosions, the D–D distance in the ultra-dense deuterium was determined to be constant at 2.3 pm. Using a long TOF-MS path now gives improved resolution. We show the strong effect of collisions in the ultra-dense material, and demonstrate that the kinetic energy of the ions increases with laser pulse power but that the number of ions formed is independent of the laser pulse power. This indicates special properties of the material. We also show that the two forms of condensed deuterium D(1) and D(−1) can be observed simultaneously as well resolved mass spectra of different forms. No intermediate bond lengths are observed. The two forms of deuterium are stable and well separated in bond length. We suggest that they switch rapidly back and forth as predicted by theory. A loosely built form with planar clusters of D(1) is observed here to be related to D(−1) formation.
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| 3. |
- Andersson, Patrik U, 1970, et al.
(författare)
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Water Condensation on Graphite Studied by Elastic Helium Scattering and Molecular Dynamics Simulations
- 2007
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 111:42, s. 15258-15266
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Tidskriftsartikel (refereegranskat)abstract
- Formation of water/ice layers on graphite has been studied in the temperature range from 90 to 180 K by elastic helium scattering, light scattering, and molecular dynamics simulations. Combined helium- and light-scattering experiments show that an ice film that wets the graphite surface is formed at surface temperatures of 100-140 K, whereas three-dimensional ice structures are formed at 140-180 K. Desorption of adsorbed water molecules competes with water incorporation into the ice film, and the ice formation rate is strongly temperature dependent. At 150 K, ice-layer formation takes place at the same time scale as layer reconstruction, and its properties are sensitive to the water deposition rate. The experimental results are compared with kinetics models, and the Johnston-Mehl-Avrami-Kolmogorov model is concluded to well describe the ice-layer formation kinetics in the whole temperature range. Molecular dynamics simulations of water-cluster formation on graphite at 90-180 K show that water molecules and small clusters are highly mobile on the surface, which rapidly results in the nucleation of large and less mobile clusters on the surface. Clusters formed at low temperature tend to have the most molecules in direct contact with the uppermost graphite layer, while multilayer cluster structures are preferred at high temperatures. The results are discussed and compared with earlier studies of water ice formation on solid surfaces.
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| 4. |
- Badiei, Shahriar, 1969, et al.
(författare)
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Fusion reactions in high-density hydrogen: A fast route to small-scale fusion?
- 2009
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Ingår i: International Journal of Hydrogen Energy. ; 34, s. 487-495
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Tidskriftsartikel (refereegranskat)abstract
- High-density atomic hydrogen, which is believed to be a quantum liquid, can be formed by heterogeneous catalysis at the surface of hydrogen-transfer metal oxide catalysts. Extensive studies have been made of the hydrogen phase named H(1), with interatomic distance of 150 pm found by Coulomb explosion measurements. This bond distance corresponds to a material density of 0.5–0.7 kgdm-3. The use of this material as fusion target for inertial confinement fusion (ICF) is proposed in J Fusion Energy 2008;27:296–300. A much denser hydrogen (deuterium) material D(-1) also exists with an interatomic distance of 2.3 pm. This material is probably the inverse of metallic D(1), where nuclei and electrons exchange their roles. The ICF process would be greatly simplified if the intended initial multi-laser compression stage was not necessary. The close-packed density of D(-1) is calculated from the bond distance as >130 kg cm-3. This is much higher than that required for ‘‘fast ignition’’ laser-driven fusion (>0.3 kg cm-3). It may mean that a method already exists to prepare dense hydrogen fuel for small-scale laser-driven fusion. The high energy particles observed experimentally (up to 150 keV/atomic mass unit in the peak or 10^9 K) indicate that high energy processes exist at relatively low laser intensities.
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| 5. |
- Badiei, Shahriar, 1969, et al.
(författare)
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High-energy Coulomb explosions in ultra-dense deuterium: Time-of-flight-mass spectrometry with variable energy and flight length
- 2009
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Ingår i: International Journal of Mass Spectrometry. - : Elsevier BV. - 1387-3806. ; 282, s. 70-76
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Tidskriftsartikel (refereegranskat)abstract
- High-density hydrogen is of great interest both as a fuel with the highest energy content of any combustion fuel, and as a target material for laser initiated inertial confinement fusion (ICF) [S. Badiei, L. Holmlid, J. Fusion Energ. 27 (2008) 296]. A much denser deuterium material named D(−1) can be observed by pulsed laser induced Coulomb explosions giving a well-defined, high kinetic energy release (KER). Neutral time-of-flight of the fragments from the material shows that the Coulomb explosions have a KER of 630 eV [S. Badiei, P.U. Andersson, L. Holmlid, Int. J. Hydrogen Energ. 34 (2009) 487]. By using ion time-of-flight-mass spectrometry (TOF-MS) with variable acceleration voltages and a few different values of laser pulse power, we now prove the mass and charge of the particles as well as the KER. In fact, the ions are so fast that they must be H+, D+ or T+. By using two different flight lengths, we prove with certainty that the spectra are due to D+ ions and not to photons or electromagnetic effects. The results also establish the fragmentation patterns of the ultra-dense D(−1) material in the electric field. The energy release of 630 ± 30 eV corresponds to an interatomic distance D–D of 2.3 ± 0.1 pm. This material is probably an inverted metal with the deuterons moving in the field from the stationary electrons, which gives a predicted interatomic distance of 2.5 pm, close to the measured value. Thus, we prove that an ultra-dense deuterium material exists.
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| 6. |
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| 7. |
- Hansen, Klavs, 1958, et al.
(författare)
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Activation energies for evaporation from protonated and deprotonated water clusters from mass spectra
- 2009
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Ingår i: journal of chemical physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 131
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Tidskriftsartikel (refereegranskat)abstract
- Experimental mass abundance spectra are used to extract evaporative activation energies (dissociation energies) for protonated water clusters, (H$_2$O)$_N$H$^+$, and deprotonated water clusters, (H$_2$O)$_N$ OH$^-$, in the size range up to hundred molecules. The inversion is achieved by application of the shell correction method adapted from nuclear physics to the abundance spectra. The well known abundance anomaly for protonated clusters which occurs for $N = 20-22$ is found to have the characteristic behavior of a shell closing, whereas other apparent magic numbers are only prominent peaks in the abundance spectra because of the instability of the evaporative precursor. For the deprotonated clusters, we find a similar shell closing for $N = 55-56$.
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| 8. |
- Janhäll, Sara, 1965, et al.
(författare)
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Evolution of the urban aerosol during winter temperature inversion episodes
- 2006
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 40:28, s. 5355-5366
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Tidskriftsartikel (refereegranskat)abstract
- Winter temperature inversions are for Nordic urban sites a major cause for exceeding air-quality legislation thresholds for most primary pollutants. In this study, number particle size distributions have been measured and compared to other tracers for traffic emissions. Concentrations during winter days with and without morning temperature inversion were compared. Morning temperature inversion resulted in high concentrations of traffic-related pollutants, including CO, NO and NO2 together with ultrafine particles, while the pollution levels where considerably lower during mornings without temperature inversion. The specific time trends of NOx species could be well understood when considering the reaction with O-3. The two different particle measures used in this study, i.e. the number concentration of ultrafine particles (10-100 nm) and the mass of particles below 10 pm (PM10), both increased during morning rush hours. When the morning inversion broke up and ground-level air mixed with air aloft, the number of particles decreased more rapidly than PM10 concentrations. LIDAR measurements were used to follow the vertical distribution of particles, and they clearly showed how the mixing processes started after the morning inversion and resulted in rising of the inversion followed by a relatively well-mixed boundary layer with a height of I kin around 14:00. (c) 2006 Elsevier Ltd. All rights reserved.
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| 9. |
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| 10. |
- Olofson, K. Frans G., 1976, et al.
(författare)
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Urban aerosol evolution and particle formation during wintertime temperature inversions
- 2009
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 43, s. 340-346
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Tidskriftsartikel (refereegranskat)abstract
- Aerosol temporal and spatial distributions during wintertime temperature inversions in Gothenburg, Sweden, have been characterized by ground-based and airborne particle measurements combined with lidar measurements. Ground inversions frequently developed during evenings and nights with stable cold conditions, and the low wintertime insolation often resulted in near neutral boundary layer conditions during day-time. Under these conditions ground level aerosol concentrations peaked during morning rush hours and often remained relatively high throughout the day due to inefficient ventilation. The particle number concentrations decreased slowly with increasing altitude within the boundary layer, and measurements slightly above the boundary layer suggested limited entrainment of polluted air into the free troposphere. High concentrations of ultrafine particles were observed throughout the boundary layer up to altitudes of 1100 m, which suggested that nucleation took place within the residual layer during the night and early morning. Recently formed particles were also observed around midday when the layer near ground was ventilated by mixing into the boundary layer, which indicated that ultrafine particles were either transported down from the residual layer to ground level or formed when the polluted surface layer mixed with the cleaner air above.
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| 11. |
- Petrignani, Annemieke, et al.
(författare)
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Dissociative recombination of the weakly bound NO-dimer cation: cross sections and three-body dynamics.
- 2005
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Ingår i: The Journal of chemical physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 123:19
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Tidskriftsartikel (refereegranskat)abstract
- Dissociative recombination (DR) of the dimer ion (NO)(2) (+) has been studied at the heavy-ion storage ring CRYRING at the Manne Siegbahn Laboratory, Stockholm. The experiments were aimed at determining details on the strongly enhanced thermal rate coefficient for the dimer, interpreting the dissociation dynamics of the dimer ion, and studying the degree of similarity to the behavior in the monomer. The DR rate reveals that the very large efficiency of the dimer rate with respect to the monomer is limited to electron energies below 0.2 eV. The fragmentation products reveal that the breakup into the three-body channel NO+O+N dominates with a probability of 0.69+/-0.02. The second most important channel yields NO+NO fragments with a probability of 0.23+/-0.03. Furthermore, the dominant three-body breakup yields electronic and vibrational ground-state products, NO(upsilon=0)+N((4)S)+O((3)P), in about 45% of the cases. The internal product-state distribution of the NO fragment shows a similarity with the product-state distribution as predicted by the Franck-Condon overlap between a NO moiety of the dimer ion and a free NO. The dissociation dynamics seem to be independent of the NO internal energy. Finally, the dissociation dynamics reveal a correlation between the kinetic energy of the NO fragment and the degree of conservation of linear momentum between the O and N product atoms. The observations support a mechanism in which the recoil takes place along one of the NO bonds in the dimer.
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| 12. |
- Romero Lejonthun, Liza, 1973, et al.
(författare)
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Chlorine interactions with water ice studied by molecular beam techniques.
- 2006
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Ingår i: The journal of physical chemistry. B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 110:46, s. 23497-501
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Tidskriftsartikel (refereegranskat)abstract
- The kinetics of chlorine interactions with ice at temperatures between 103 and 165 K have been studied using molecular beam techniques. The Cl(2) trapping probability is found to be unity at thermal incident energies, and trapping is followed by rapid desorption. The residence time on the surface is less than 25 microg at temperatures above 135 K and approaches 1 s around 100 K. Rate constants for desorption are determined for temperatures below 135 K. The desorption kinetics follow the Arrhenius equation, and activation energies of 0.24 +/- 0.03 and 0.31 +/- 0.01 eV, with corresponding preexponential factors of 10(12.08+/-1.19) and 10(16.52+/-0.38) s(-1), are determined. At least two different Cl(2) binding sites are concluded to exist on the ice surface. The observed activation energies are likely to be the Cl(2)-ice binding energies for these states, and the Cl(2)-surface interactions are concluded to be stronger than earlier theoretical estimates. The surface coverage of Cl(2) on ice under stratospheric conditions is estimated to be negligible, in agreement with earlier work.
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| 13. |
- Romero Lejonthun, Liza, 1973, et al.
(författare)
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Formation of Adsorbed Layers by Deposition of Dinitrogen Pentoxide, Nitric Acid, and Water on Graphite
- 2009
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Ingår i: J. Phys. Chem. C. - : American Chemical Society (ACS). ; 113, s. 7728-7734
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Tidskriftsartikel (refereegranskat)abstract
- The formation of adsorbed layers of dinitrogen pentoxide, nitric acid, and water on graphite has been studied by molecular beam and light-scattering techniques. The desorption kinetics of N2O5 on graphite were described by the Arrhenius equation with an activation energy of 0.24 ± 0.03 eV and a pre-exponential factor of 2.3 × 10(10 ± 0.73) s−1, and N2O5 is concluded to bind more strongly than H2O to the graphite surface. Elastic helium scattering and light scattering were used to probe the formation of adlayers on the surface. Adsorption of pure N2O5 resulted in formation of thin adlayers at temperatures below 160 K. In coadsorption experiments N2O5 was concluded to facilitate the formation of thick N2O5−H2O ice layers at 155 K. In a similar way coadsorption of HNO3 and H2O resulted in the formation of thick adlayers at 170 K. N2O5 and HNO3 both bind more strongly than water to the graphite surface and are concluded to facilitate nucleation and growth of ice.
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| 14. |
- Suter, Martina, 1966, et al.
(författare)
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Argon collisions with amorphous water ice surfaces
- 2006
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Ingår i: Chemical Physics. ; 326:2-3, s. 281-288
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Tidskriftsartikel (refereegranskat)abstract
- The dynamics of argon atom collisions with amorphous ice surfaces are investigated using molecular beam techniques and molecular dynamics simulations. The formation of an amorphous ice layer on top of crystalline ice at 110 K is shown to have a strong influence on Ar scattering. Compared to crystalline ice, trapping followed by desorption is favoured over inelastic scattering, and a strongly enhanced emission of argon in the backward direction is observed. Molecular dynamics simulation with different types of amorphous and crystalline surfaces are consistent with the experimental data and show that large scale corrugation is required to reproduce the experimental findings. It is concluded that argon scattering can be used to probe changes in surface structure on the nanometer length-scale, while it is relatively insensitive to changes on the molecular level, and it thereby complements other techniques for studies of structural changes of ice surfaces. (c) 2006 Elsevier B.V. All rights reserved.
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| 15. |
- Suter, Martina, 1966, et al.
(författare)
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Formation of water-ammonia ice on graphite studied by elastic helium scattering
- 2007
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 445, s. 208-212
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Tidskriftsartikel (refereegranskat)abstract
- Helium and light scattering experiments have been performed to study the formation of water–ammonia ice layers on graphite at 110–160 K. Ice formation is mainly governed by the partial water pressure, but the presence of ammonia enhances the formation rate and influences the layer properties. Ice formed at temperatures <140 K wets the surface, while ice formed at higher temperatures does not. At temperatures around 140 K ammonia destabilizes the two-dimensional ice layers and a dewetting transition is observed at a surface coverage of 90–95%.
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| 16. |
- Suter, Martina, 1966, et al.
(författare)
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Surface properties of water ice at 150-191 K studied by elastic helium scattering.
- 2006
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Ingår i: The Journal of chemical physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 125:17
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Tidskriftsartikel (refereegranskat)abstract
- A highly surface sensitive technique based on elastic scattering of low-energy helium atoms has been used to probe the conditions in the topmost molecular layer on ice in the temperature range of 150-191 K. The elastically scattered intensity decreased slowly as the temperature was increased to about 180 K, followed by a rapid decrease at higher temperatures. An effective surface Debye temperature of 185+/-10 K was calculated from the data below 180 K. The changes in the ice surface above 180 K are interpreted as the onset of an anomalous enhancement of the mean square vibrational amplitude for the surface molecules and/or the onset of a limited amount of disorder in the ice surface. The interpretation is consistent with earlier experimental studies and molecular dynamics simulations. The observed changes above 180 K can be considered as the first sign of increased mobility of water molecules in the ice surface, which ultimately leads to the formation of a quasiliquid layer at higher temperatures. A small shift and broadening of the specular peak was also observed in the range of 150-180 K and the effect is explained by the inherent corrugation of the crystalline ice surface. The peak shift became more pronounced with increasing temperature, which indicates that surface corrugation increases as the temperature approaches 180 K. The results have implications for the properties and surface chemistry of atmospheric ice particles, and may contribute to the understanding of solvent effects on the internal molecular motion of hydrated proteins and other organic structures such as DNA.
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| 17. |
- Svane, Maria, 1957, et al.
(författare)
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On-Line Chemical Analysis of Individual Alkali-Containing Aerosol Particles by Surface Ionization Combined with Time-of-Flight Mass Spectrometry
- 2009
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Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 0278-6826 .- 1521-7388. ; 43:7, s. 653-661
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Tidskriftsartikel (refereegranskat)abstract
- An aerosol mass spectrometer for measurements of the alkali metal content in individual submicron aerosol particles is presented. The instrument combines surface ionization of individual particles on a hot platinum surface with orthogonal acceleration time-of-flight mass spectrometry. The instrument simultaneously provides the content of different alkali metal elements in single particles with high sensitivity. The instrument is characterized in laboratory experiments, and determination of the alkali metal content is demonstrated for particle diameters of 50-500 nm. The technique is demonstrated in ambient air measurements at an urban background site, and sea spray particles and particles originating from biomass burning are identified based on their content of sodium and potassium. Possible further improvements and applications of the technique are discussed.
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| 18. |
- Vigren, Erik, et al.
(författare)
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Dissociative recombination of fully deuterated protonated acetonitrile, CD3CND+ : Product branching fractions, absolute cross section and thermal rate coefficient
- 2008
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 10, s. 4014-4019
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Tidskriftsartikel (refereegranskat)abstract
- The dissociative recombination of fully deuterated protonated acetonitrile, CD3CND+, has been investigated at the CRYRING heavy ion storage ring, located at the Manne Siegbahn Laboratory, Stockholm, Sweden. Branching fractions were measured at similar to 0 eV relative collision energy between the ions and the electrons and in 65% of the DR events there was no rupture of bonds between heavy atoms. In the remaining 35%, one of the bonds between the heavy atoms was broken. The DR cross-section was measured between similar to 0 eV and 1 eV relative collision energy. In the energy region between 1 meV and 0.1 eV the cross section data were best fitted by the expression sigma = 7.37 x 10(-16) (E/eV)(-1.23) cm(2), whereas sigma = 4.12 x 10(-16) (E/eV)(-1.46) cm(2) was the best fit for the energy region between 0.1 and 1.0 eV. From the cross section a thermal rate coefficient of alpha(T) = 8.13 x 10(-7) (T/300)(-0.69) cm(3) s(-1) was deduced.
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| 19. |
- Öjekull, Jenny, 1973, et al.
(författare)
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Dissociative recombination of ammonia clusters studied by storage ring experiments
- 2006
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 125:19, s. 194306-
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Tidskriftsartikel (refereegranskat)abstract
- Dissociative recombination of ammonia cluster ions with free electrons has been studied at the heavy-ion storage ring CRYRING (Manne Siegbahn Laboratory, Stockholm University). The absolute cross sections for dissociative recombination of H+(NH3)(2), H+(NH3)(3), D+(ND3)(2), and D+(ND3)(3) in the collision energy range of 0.001-27 eV are reported, and thermal rate coefficients for the temperature interval from 10 to 1000 K are calculated from the experimental data and compared with earlier results. The fragmentation patterns for the two ions H+(NH3)(2) and D+(ND3)(2) show no clear isotope effect. Dissociative recombination of X+(NX3)(2) (X=H or D) is dominated by the product channels 2NX(3)+X [0.95 +/- 0.02 for H+(NH3)(2) and 1.00 +/- 0.02 for D+(ND3)(2)]. Dissociative recombination of D+(ND3)(3) is dominated by the channels yielding three N-containing fragments (0.95 +/- 0.05).
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| 20. |
- Öjekull, Jenny, 1973, et al.
(författare)
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Dissociative recombination of H+(H2O)3 and D+(D2O)3 water cluster ions with electrons: Cross sections and branching ratios
- 2007
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Ingår i: The Journal of chemical physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 127, s. 194301-194309
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Tidskriftsartikel (refereegranskat)abstract
- Dissociative recombination (DR) of the water cluster ions H+(H2O)3 and D+(D2O)3 with electrons has been studied at the heavy-ion storage ring CRYRING (Manne Siegbahn Laboratory, Stockholm University). For the first time, absolute DR cross sections have been measured for H+(H2O)3 in the energy range of 0.001–0.8 eV, and relative cross sections have been measured for D+(D2O)3 in the energy range of 0.001–1.0 eV. The DR cross sections for H+(H2O)3 are larger than previously observed for H+(H2O)n (n=1,2), which is in agreement with the previously observed trend indicating that the DR rate coefficient increases with size of the water cluster ion. Branching ratios have been determined for the dominating product channels. Dissociative recombination of H+(H2O)3 mainly results in the formation of 3H2O+H (probability of 0.95±0.05) and with a possible minor channel resulting in 2H2O+OH+H2 (0.05±0.05). The dominating channels for DR of D+(D2O)3 are 3D2O+D (0.88±0.03) and 2D2O+OD+D2 (0.09±0.02). The branching ratios are comparable to earlier DR results for H+(H2O)2 and D+(D2O)2, which gave 2X2O+X (X=H,D) with a probability of over 0.9.
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| 21. |
- Öjekull, Jenny, 1973, et al.
(författare)
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Dissociative recombination of water cluster ions with free electrons : Cross sections and branching ratios
- 2008
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 128:4, s. 44311-
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Tidskriftsartikel (refereegranskat)abstract
- Dissociative recombination (DR) of water cluster ions H+(H2O)(n) (n=4-6) with ree electrons has been studied at the heavy-ion storage ring CRYRING (Manne Siegbahn Laboratory, Stockholm University). For the first time, branching ratios have been determined for the dominating product channels and absolute DR cross sections have been measured in the energy range from 0.001 to 0.7 eV. Dissociative recombination is concluded to result in extensive fragmentation for all three cluster ions, and a maximum number of heavy oxygen-containing fragments is produced with a probability close to unity. The branching ratio results agree with earlier DR studies of smaller water cluster ions where the channel nH(2)O+H has been observed to dominate and where energy transfer to internal degrees of freedom has been concluded to be highly efficient. The absolute DR cross sections for H+(H2O)(n) (n=4-6) decrease monotonically with increasing energy with an energy dependence close to E-1 in the lower part of the energy range and a faster falloff at higher energies, in agreement with the behavior of other studied heavy ions. The cross section data have been used to calculate DR rate coefficients in the temperature range of 10-2000 K. The results from storage ring experiments with water cluster ions are concluded to partly confirm the earlier results from afterglow experiments. The DR rate coefficients for H+(H2O)(n) (n=1-6) are in general somewhat lower than reported from afterglow experiments. The rate coefficient tends to increase with increasing cluster size, but not in the monotonic way that has been reported from afterglow experiments. The needs for further experimental studies and for theoretical models that can be used to predict the DR rate of polyatomic ions are discussed.
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