| 1. |
- Najeeb, P. K., et al.
(author)
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Spontaneous decay of small carbon cluster dianions C-n(2-) (n=7-11)
- 2020
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In: Journal of Physics, Conference Series, Vol 1412, Article 232014. - : IOP Publishing. - 1742-6588 .- 1742-6596.
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Conference paper (peer-reviewed)abstract
- We have studied the stabilities of small carbon dianion clusters, C-n(2-) (n=7-11) in the cryogenic electrostatic ion storage ring, DESIREE. We observe spontaneous electron emission for tens of milliseconds, where dianions containing an even number of carbons decay slower in comparison to their neighbouring cluster sizes. For all the systems considered here, we find that there is a component which is stable at least on the time scales of hundreds of milliseconds.
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| 2. |
- Najeeb, P. K., 1986-, et al.
(author)
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Stability and Cooling of the C72- Dianion
- 2023
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 131:11
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Journal article (peer-reviewed)abstract
- We have studied the stability of the smallest long-lived all carbon molecular dianion (C72-) in new time domains and with a single ion at a time using a cryogenic electrostatic ion-beam storage ring. We observe spontaneous electron emission from internally excited dianions on millisecond timescales and monitor the survival of single colder C72- molecules on much longer timescales. We find that their intrinsic lifetime exceeds several minutes - 6 orders of magnitude longer than established from earlier experiments on C72-. This is consistent with our calculations of vertical electron detachment energies predicting one inherently stable isomer and one isomer which is stable or effectively stable behind a large Coulomb barrier for C72-→C7-+e- separation.
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| 3. |
- Najeeb, P. K., 1986-, et al.
(author)
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Stability and Cooling of the C2−7 Dianion
- 2023
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 131:11
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Journal article (peer-reviewed)abstract
- We have studied the stability of the smallest long-lived all carbon molecular dianion () in new time domains and with a single ion at a time using a cryogenic electrostatic ion-beam storage ring. We observe spontaneous electron emission from internally excited dianions on millisecond timescales and monitor the survival of single colder molecules on much longer timescales. We find that their intrinsic lifetime exceeds several minutes—6 orders of magnitude longer than established from earlier experiments on . This is consistent with our calculations of vertical electron detachment energies predicting one inherently stable isomer and one isomer which is stable or effectively stable behind a large Coulomb barrier for →+e− separation.
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| 4. |
- Gnaser, H., et al.
(author)
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Spontaneous and photo-induced decay processes of WF5- and HfF5- molecular anions in a cryogenic storage ring
- 2022
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In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 157:4
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Journal article (peer-reviewed)abstract
- Spontaneous and photo-induced decay processes of HfF5- and WF5- molecular anions were investigated in the Double ElectroStatic Ion Ring ExpEriment (DESIREE). The observation of these reactions over long time scales (several tens of ms) was possible due to the cryogenic temperatures (13 K) and the extremely low residual gas pressure (similar to 10(-14) mbar) of DESIREE. For photo-induced reactions, laser wavelengths in the range 240 to 450 nm were employed. Both anion species were found to undergo spontaneous decay via electron detachment or fragmentation. After some ms, radiative cooling processes were observed to lower the probability for further decay through these processes. Photo-induced reactions indicate the existence of an energy threshold for WF5- anions at about 3.5 eV, above which the neutralization yield increases strongly. By contrast, HfF5- ions exhibit essentially no enhanced production of neutrals upon photon interaction, even for the highest photon energy used in this experiment (similar to 5.2 eV). This suppression will be highly beneficial for the efficient detection, in accelerator mass spectrometry, of the extremely rare isotope Hf-182 using the Hf-182-F-5(-) anion while effectively reducing the interfering stable isobar W-182 in the analyte ion (WF5-)-W-182. The radionuclide Hf-182 is of great relevance in astrophysical environments as it constitutes a potential candidate to study the events of nucleosynthesis that may have taken place in the vicinity of the solar system several million years Published under an exclusive license by AIP Publishing.
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