| 1. |
- Hartman, Henrik, et al.
(författare)
-
Negative ion relaxation and reactions in a cryogenic storage ring
- 2020
-
Ingår i: Journal of Physics: Conference Series Vol 1412. - : IOP Publishing. - 1742-6588 .- 1742-6596.
-
Konferensbidrag (refereegranskat)abstract
- An overview of recent experimental results of studies of negative atomic and molecular ions in the Double ElectroStatic Ion-Ring ExpEriment, DESIREE is given. Metastable level lifetimes in atomic negative ions have been measured by time-dependent laser photodetachment. Rotational relaxation of diatomic anions is studied by near-threshold photodetachment. Spontaneous decays of small metal cluster anions by electron emission and fragmentation is studied with decay-channel specificity. Finally, mutual neutralisation of pairs of negative and positive ions has been investigated with initial and final state selectivity.
|
|
| 2. |
- Anderson, Emma K., 1986-, et al.
(författare)
-
Fragmentation of and electron detachment from hot copper and silver dimer anions : A comparison
- 2023
-
Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - 2469-9926 .- 2469-9934. ; 107:6
-
Tidskriftsartikel (refereegranskat)abstract
- We measured the spontaneous decays of internally hot copper and silver dimer anions, and , stored in one of the two ion-beam storage rings of the Double Electrostatic Ion Ring Experiment (DESIREE) at Stockholm University. A coincidence detection technique was utilized enabling essentially background-free measurements of -> Cu + Cu- and -> Ag + Ag- fragmentation rates. Furthermore, the total rates of neutral decay products (monomers and dimers) were measured and the relative contributions of fragmentation and electron emission ( -> Cu2 + e- and -> Ag2 + e-) were deduced as functions of storage time. Fragmentation is completely dominant at early times. However, after about 20 ms of storage, electron emission is observed and becomes the leading decay path after 100 ms for both dimer anions. The branching ratios between fragmentation and electron emission (vibrationally assisted autodetachment processes) are very nearly the same for and Ag-2 throughout the present storage cycle of 10 seconds. This is surprising considering the difference between the electron affinities of the neutral dimers, Cu2 and Ag2, and the difference between the and the dissociation energies.
|
|
| 3. |
- Najeeb, P. K., et al.
(författare)
-
Spontaneous decay of small carbon cluster dianions C-n(2-) (n=7-11)
- 2020
-
Ingår i: Journal of Physics, Conference Series, Vol 1412, Article 232014. - : IOP Publishing. - 1742-6588 .- 1742-6596.
-
Konferensbidrag (refereegranskat)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.
|
|
| 4. |
- Najeeb, P. K., 1986-, et al.
(författare)
-
Stability and Cooling of the C72- Dianion
- 2023
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 131:11
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 5. |
- Najeeb, P. K., 1986-, et al.
(författare)
-
Stability and Cooling of the C2−7 Dianion
- 2023
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 131:11
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 6. |
- Eklund, G., et al.
(författare)
-
Final state resolved mutual neutralization of Li+ and D-
- 2020
-
Ingår i: 31St International Conference On Photonic, Electronic And Atomic Collisions (Icpeac Xxxi). - : IOP PUBLISHING LTD.
-
Konferensbidrag (refereegranskat)abstract
- We have performed a merged beam experiment on mutual neutralization of Li+ and D-, at center of mass energies close to 0 eV using the DESIREE storage rings. The final state channels Li(3s) and Li(3p+3d) are resolved and the branching ratio is found to be more equal than predicted from theoretical models.
|
|
