Speaker
Description
In multi-electron systems such as atoms and molecules, the electron-electron interaction poses a major challenge for the accurate theoretical description of atomic structure and dynamics, requiring sophisticated numerical approaches. These theoretical models are then also used to provide required information for experimental analysis such as for nuclear square charge radii determinations from isotope shift measurements [1].
Negative ions can serve as excellent probes for these tests, in addition to a variety of applications in other fields [2-4]: since the Coulomb potential of the nucleus is almost entirely screened, the binding of the additional electron in a negative ion is primarily due to the many body interactions between electrons. Consequently, negative ions are sensitive probes of these effects.
However, due to the weak binding potential, the energy gained by attaching an electron to a neutral atom, referred to as electron affinity (EA), is typically only in the order of one eV. For the same reason, negative ions typically lack bound excited states with opposite parity, noticeable exceptions being lanthanum, cerium, osmium, thorium and uranium [5-9]. Consequently, the EA is the only parameter which can be probed with high precision, typically via laser photodetachment threshold spectroscopy (LPTS).
In this talk, we will present recent results of laser photodetachment experiments to determine lifetimes and binding energies of atomic negative ions, performed at the Gothenburg University Negative Ion LAboratory (GUNILLA), the electrostatic storage ring DESIREE in Stockholm and ISOLDE.
References
[1] J.Z. Han et al., Phys. Rev. Research 4, 033049 (2022)
[2] G. Cerchiari et al., Phys. Rev. Lett. 120 (2018)
[3] T. J. Millar, et al., Chemical reviews 117.3 (2017)
[4] D. E. Post et al., INIS 22 (1991).
[5] R. Tang et al., American Physical Society 123, 20 (2019).
[6] C. Walter et al., Phys. Rev. A 76, (2007).
[7] R. Bilodeau and H.K. Haugen, Phys. Rev. Lett. 85, 3 (2000).
[8] C. Walter et al., Phys. Rev. Lett. 113, 6 (2014).
[9] R. Tang et al., Phys. Rev. A 103, L050801 (2021).
