| 1. |
- Zöttl, S., et al.
(författare)
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Energy harvesting in doped helium nano-droplets
- 2012
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Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 388:13, s. 132003-
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Tidskriftsartikel (refereegranskat)abstract
- We report the observation of sequential Penning ionization of dopants by metastable helium atoms in helium nano-droplets resulting in doubly charged ions. Strong charge induced dipole-interaction between the excited helium atom and the target ion provides a high probability for the transfer of the internal energy of the excited helium atom to the dopant ion. This process may also lead subsequently to a Coulomb explosion of molecular or cluster dopants.
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| 2. |
- Denifl, S, et al.
(författare)
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Ionization of doped helium nanodroplets : Complexes of C-60 with water clusters
- 2010
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Ingår i: Journal of Chemical Physics. - : American Institute of Physics. - 0021-9606 .- 1089-7690. ; 132:23, s. 234307-
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Tidskriftsartikel (refereegranskat)abstract
- Water clusters are known to undergo an autoprotonation reaction upon ionization by photons or electron impact, resulting in the formation of (H2O)(n)H3O+. Ejection of OH cannot be quenched by near-threshold ionization; it is only partly quenched when clusters are complexed with inert gas atoms. Mass spectra recorded by electron ionization of water-doped helium droplets show that the helium matrix also fails to quench OH loss. The situation changes drastically when helium droplets are codoped with C-60. Charged C-60-water complexes are predominantly unprotonated; C-60(H2O)(4)(+) and (C-60)(2)(H2O)(4)(+) appear with enhanced abundance. Another intense ion series is due to C-60(H2O)(n)OH+; dehydrogenation is proposed to be initiated by charge transfer between the primary He+ ion and C-60. The resulting electronically excited C-60(+)* leads to the formation of a doubly charged C-60-water complex either via emission of an Auger electron from C-60(+)*, or internal Penning ionization of the attached water complex, followed by charge separation within {C-60(H2O)(n)}(2+). This mechanism would also explain previous observations of dehydrogenation reactions in doped helium droplets. Mass-analyzed ion kinetic energy scans reveal spontaneous (unimolecular) dissociation of C-60(H2O)(n)(+). In addition to the loss of single water molecules, a prominent reaction channel yields bare C-60(+) for sizes n=3, 4, or 6. Ab initio Hartree-Fock calculations for C-60-water complexes reveal negligible charge transfer within neutral complexes. Cationic complexes are well described as water clusters weakly bound to C-60(+). For n=3, 4, or 6, fissionlike desorption of the entire water complex from C-60(H2O)(n)(+) energetically competes with the evaporation of a single water molecule. (C) 2010 American Institute of Physics.
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| 3. |
- Mauracher, Andreas, et al.
(författare)
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Metastable anions of dinitrobenzene : Resonances for electron attachment and kinetic energy release
- 2010
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 133:24, s. 244302-
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Tidskriftsartikel (refereegranskat)abstract
- Attachment of free, low-energy electrons to dinitrobenzene (DNB) in the gas phase leads to DNB− as well as several fragment anions. DNB−, (DNB-H)−, (DNB-NO)−, (DNB-2NO)−, and (DNB-NO2)− are found to undergo metastable (unimolecular) dissociation. A rich pattern of resonances in the yield of these metastable reactions versus electron energy is observed; some resonances are highly isomer-specific. Most metastable reactions are accompanied by large average kinetic energy releases (KER) that range from 0.5 to 1.32 eV, typical of complex rearrangement reactions, but (1,3-DNB-H)− features a resonance with a KER of only 0.06 eV for loss of NO. (1,3-DNB-NO)− offers a rare example of a sequential metastable reaction, namely, loss of NO followed by loss of CO to yield C5H4O− with a large KER of 1.32 eV. The G4(MP2) method is applied to compute adiabatic electron affinities and reaction energies for several of the observed metastable channels
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