In: The Journal of Chemical Physics, 2014, vol. 140, no. 21, p. 214314
We present an experimental study of the laser-induced luminescence spectra of Mn atoms in solid helium matrices. We observe transitions of the valence electron and of inner-shell electrons. We find that the Mn-He interaction perturbs the inner-shell transitions to a lesser extent than the valence-electron transitions. The observed lineshapes of the inner-shell transitions of Mn are similar to...
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In: The Journal of Chemical Physics, 2013, vol. 139, no. 10, p. 104307
We present a systematic experimental study of absorption and fluorescence spectra of Au atoms in bulk liquid and solid helium matrices. The results are compared to the spectra of Cu atoms studied earlier. We investigate the dependence of the observed spectral lineshapes on the helium pressure. The observed splitting of the 5d 106p − 5d 96s 2 transitions of Au in hcp solid He gives evidence for...
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In: Physical Review A, 2013, vol. 87, no. 2, p. 022513
We present an experimental study of laser-induced fluorescence spectra of Cs atoms embedded in superfluid and solid ⁴He, as well as in dense supercritical fluid He. The studied temperature range is increased with respect to earlier studies by the use of intense laser pulses for the transient local heating of the helium sample. The analysis of the experimental spectra is based on two different...
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In: Physical Review A - Atomic, Molecular and Optical Physics, 2011, vol. 84, no. 5, p. 052519
We present an experimental study of the laser-induced fluorescence spectra of Cu atoms in bulk liquid and solid helium matrices as well as in the dense plasma created by the laser ablation of copper in liquid helium. We observe transitions of the valence electron and of inner-shell electrons. The former produce structureless line shapes, a large broadening, and a blueshift. The latter practically...
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In: The Journal of Physical Chemistry A, 2011, vol. 115, no. 25, p. 7169–7179
We analyze the effect of the host crystal symmetry on the optical spectra of the 6P1/2−6S1/2 and 6P3/2−6S1/2 transitions of atomic Cs in solid ⁴He matrices. In particular, we address the deformation of the bubble structures formed by Cs in such quantum crystals. We show that the anisotropy of the stiffness tensor leads...
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In: Physical Review A - Atomic, Molecular and Optical Physics, 2011, vol. 84, no. 2, p. 022502
We present an exhaustive overview of optical absorption and laser-induced fluorescence lines of Ba atoms in liquid and solid helium matrices in visible and near-infrared spectral ranges. Due to the increased density of isolated atoms, we have found a large number of spectral lines that were not observed in condensed helium matrices before. We have also measured the lifetimes of metastable states....
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In: Europhysics Letters, 2010, vol. 90, no. 3, p. 34002
We demonstrate that laser ablation of a gold target immersed in superfluid and normal fluid helium leads to the formation of elongated gold nano-fragments. In the superfluid phase these nano-fragments aggregate into filaments with extremely large aspect ratios displaying metallic electric conductivity. We attribute this unusual structure to the coalescence of gold particles trapped on quantized...
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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...
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In: Physical Review Letters, 2009, vol. 102, no. 11, p. 115301
We have observed bulk solidification of ⁴He induced by nucleation on positive alkali ions in pressurized superfluid helium. The ions are extracted into the liquid from alkali-doped solid He by a static electric field. The experiments prove the existence of charged particles in a solid structure composed of doped He that was recently shown to coexist with superfluid helium below the He...
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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...
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