Université de Fribourg

Atomic bubbles in impurity-stabilized solid ⁴He

Lebedev, Victor ; Moroshkin, Peter ; Weis, Antoine

In: Fizika Nizkikh Temperatur, 2010, vol. 35, no. 4, p. 391-395

The optical absorption and fluorescence spectra of alkali atoms isolated in liquid and solid He matrices depend on specific macroscopic matrix properties, such as their molar volume and (anisotropic) elasticity constants, and provide thus information about the quantum matrix. We have applied optical spectroscopy to investigate the properties of a recently discovered impurity-stabilized doped...

Université de Fribourg

Atomic and molecular defects in solid ⁴He

Moroshkin, Peter ; Hofer, Adrian ; Weis, Antoine

In: Physics Reports, 2008, vol. 469, no. 1, p. 1-57

The studies of defects formed by impurity particles (atoms, molecules, exciplexes, clusters, free electrons, and positive ions) embedded in liquid and solid ⁴He are reviewed. The properties of free electrons and neutral particles in condensed helium are described by the electron (atomic) bubble model, whereas for the positive ions a snowball structure is considered. We compare the properties of...

Université de Fribourg

Lifetime studies of Cs*HeN exciplexes in solid ⁴He

Moroshkin, Peter ; Hofer, Adrian ; Lebedev, Victor ; Weis, Antoine

In: Physical Review A, 2008, vol. 78, p. 032501

We present time-resolved measurements of the laser-induced fluorescence from Cs atoms and Cs*HeN exciplexes in a solid ⁴He matrix. The linear Cs*He₌₂ exciplex is strongly quenched by a radiationless transformation into a ring-shaped Cs*HeN=6,7 exciplex, which decays radiatively with a lifetime of 88±2 ns. The analysis...

Université de Fribourg

Laser-based precision magnetometry in fundamental and applied research

Weis, Antoine ; Wynands, Robert

In: Optics and Lasers in Engineering, 2005, vol. 43, p. 387-401

In this paper we review research done by the recently founded Fribourg group for Atomic Physics (FRAP) using laser-assisted spin coherence spectroscopy of atomic samples in applied and fundamental physics. Spin coherence in optically pumped ensembles of paramagnetic atoms may be extremely long-lived when the samples are well shielded from external perturbations, like static or oscillating...