Ground-state hyperfine structure of the muonic helium atom

Ground State Hyperfine Structure of Muonic Helium Atom

The muonic helium atom (μe2He) represents the simple three-body atomic system. The interaction between magnetic moments of the muon and electron leads to the hyperfine structure (HFS) of the energy levels. The investigation of the energy spectrum of this atom is important for the check of quantum electrodynamics for three-particle bound state. The ground state hyperfine splitting was measured m...

Hyperfine Structure of S-states in Muonic Helium Ion

Corrections of orders α5 and α6 are calculated in the hyperfine splittings of 1S and 2S energy levels in the ion of muonic helium. The electron vacuum polarization effects, the nuclear structure corrections and recoil corrections are taken into account. The obtained numerical values of the hyperfine splittings -1334.56 meV (1S state), -166.62 meV (2S state) can be considered as a reliable estim...

The Structure of the Helium Atom.

Controlling the hyperfine state of rovibronic ground-state polar molecules.

We report the preparation of a rovibronic ground-state molecular quantum gas in a single hyperfine state and, in particular, the absolute lowest quantum state. This addresses the last internal degree of freedom remaining after the recent production of a near quantum degenerate gas of molecules in their rovibronic ground state, and provides a crucial step towards full control over molecular quan...

Ejection of quasi-free-electron pairs from the helium-atom ground state by single-photon absorption.

We investigate the single-photon double ionization of helium at photon energies of 440 and 800 eV. We observe doubly charged ions with close to zero momentum corresponding to electrons emitted back to back with equal energy. These slow ions are the unique fingerprint of an elusive quasifree photon double ionization mechanism predicted by Amusia et al. nearly four decades ago [J. Phys. B 8, 1248...