Spectroscopy and dynamics of trapped alkaline earth atoms in superfluid helium

Spectroscopy of barium atoms in liquid and solid helium matrices

“…Electronically excited Ba atoms at densities of ≈10 8 cm −3 were produced by the recombination of implanted Ba + ions with free electrons in the liquid helium bath, and the spectrum of the recombination-induced fluorescence was observed. Larger dopant densities (up to 10 10 cm −3 ) were obtained by producing Ba atoms via direct laser ablation in liquid helium, close to the observation zone [7][8][9][10]. Those studies focused on the laser-induced fluorescence (LIF) and excitation spectra of the singlet 6s 2 -6s6p transition and of the triplet 5d6s -5d6p transitions whose lowest state is the metastable 5d6s 3 D 1 .…”

“…In order to interpret the observed spectral shifts and widths, the atomic bubble model, an extension of the electron bubble model [12], was developed and refined [5,8,11,13,14]. Calculations were carried out for the 6s 2 -6s6p singlet transition and yielded line shapes in good agreement with experimental findings.…”

Atomic and molecular defects in solid 4He

“…It has been applied by several groups investigating alkali [122,123,44,74,45,94] and alkaline-earth elements [124,125,57,85,56], as well as Ag [100], Al, Yb, Ga, and In [124]. Since the laser ablation in liquid He produces mostly impurity clusters, [124,121,58,56] a second delayed laser pulse was applied in some experiments in order to dissociate the clusters and to produce individual impurity atoms. In other experiments [122,123,44,74,45,94] the same effect was achieved by increasing the repetition rate of the ablation laser up to 1 kHz.…”

Formation of Metallic Nanowires by Laser Ablation in Liquid Helium

“…Although laser ablation (LA) of metals in liquid He is used in matrix-isolation spectroscopy since the 1990's [4][5][6][7][8], the ablation process is not well studied. In particular the formation of nanoparticles (NP) during the laser ablation of Cs and Rb in liquid helium was reported [4,9].…”