The Double ElectroStatic Ion Ring ExpEriment (DESIREE) is a unique facility[1], which was constructed when CRYRING moved to GSI in Darmstadt. The setup allows for studies of ions at cryogenic temperatures of about 13K in an ultra-high vacuum, with just one particle per cubic millimeter. This makes DESIREE ideal to study ions on time scales ranging from microseconds to seconds or longer [2]. These characteristics, allow us to investigate (i) the lifetimes of specific metastable states [3], (ii) perform high precision measurements of electron affinities [4], (iii) study the cooling dynamics of molecules [5] and (iv) perform merged beam experiments, in which interactions between single anions and cations are studied [6].
In this talk, I am going to present an overview of DESIREE highlighting recent results about both single and double ring experiments. Over the past few years many different types of experiments have been conducted at DESIREE including not only atomic ions but also small molecules such as polycyclic aromatic hydrocarbon (PAH) and fullerenes. A new measurement technique allowed us to investigate knockout fragments of coronene and C60 ions, produced via hard collisions between the ions and helium atoms. These results indicate that such ions can survive in interstellar and circumstellar environments and possibly affect reaction pathways of carbonaceous molecules [7].
Furthermore, we implemented a tunable laser which allowed us to measure the photo detachment signal and determine the electron affinities of Oxygen, Silicon and C60/C70 fullerenes. In addition, the long storage times of the ions and the laser probing technique made it possible to study the cooling processes of PAH and fullerene ions in unprecedented details, showing that recurrent fluorescence plays an important role for the survival of internally hot ions. In addition, we developed the laser induced fluorescence (LIF) measurements for ion storage rings to measure the lifetime of metastable states of Ba(II) and Fe(II) improving the results obtained at the old CRYRING at the Manne Siegbahn Laboratory in Stockholm.
Finally, the two electrostatic ion storage rings share a common straight section which allows studies of mutual neutralization (MN) processes between oppositely charged ions in sub-eV collisions. Our findings from merged beam experiments provide information on the quantum states involved in these reactions.
References
[1] R. D. Thomas et al., “The double electrostatic ion ring experiment: A unique cryogenic electrostatic storage ring for merged ion-beams studies,” Rev. Sci. Instrum., vol. 82, no. 6, p. 065112, Jun. 2011, doi: 10.1063/1.3602928.
[2] H. T. Schmidt et al., “First storage of ion beams in the Double Electrostatic Ion-Ring Experiment: DESIREE,” Rev. Sci. Instrum., vol. 84, no. 5, p. 055115, May 2013, doi: 10.1063/1.4807702.
[3] M. K. Kristiansson, J. Karls, N. D. Gibson, D. Hanstorp, H. T. Schmidt, and C. W. Walter, “Measurement of the lifetime of a metastable excited state in Bi-,” Phys. Rev. A, vol. 105, no. 1, p. L010801, Jan. 2022, doi: 10.1103/PhysRevA.105.L010801.
[4] M. K. Kristiansson et al., “High-precision electron affinity of oxygen,” Nat. Commun., vol. 13, no. 1, Art. no. 1, Oct. 2022, doi: 10.1038/s41467-022-33438-y.
[5] J. W. L. Lee et al., “Cooling dynamics of energized naphthalene and azulene radical cations,” J. Chem. Phys., vol. 158, no. 17, p. 174305, May 2023, doi: 10.1063/5.0147456.
[6] A. Bogot et al., “The mutual neutralization of hydronium and hydroxide,” Science, vol. 383, no. 6680, pp. 285–289, Jan. 2024, doi: 10.1126/science.adk1950.
[7] M. Gatchell et al., “Survival of polycyclic aromatic hydrocarbon knockout fragments in the interstellar medium,” Nat. Commun., vol. 12, no. 1, p. 6646, Nov. 2021, doi: 10.1038/s41467-021-26899-0.
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Alexandre Gumberidze - Department Atomic, Quantum & Fundamental Physics