In: Physical Review A, 2006, vol. 74, p. 032509
We report the observation of emission spectra from Rb*Hen exciplexes in solid ⁴He. Two different excitation channels were experimentally identified, viz., exciplex formation via laser excitation to the atomic 5P3/2 and to the 5P1/2 levels. While the former channel was observed before in liquid helium, on helium nanodroplets, and...
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In: Physical Review A, 2007, vol. 76, no. 2, p. 022502
We present a systematic experimental study of the absorption and fluorescence spectra of the 6S1/2-6P1/2 transition in Cs atoms isolated in solid ⁴He matrices. The bubble model developed earlier for alkali-metal atoms in liquid He is revised and applied to the present system. The analysis of the dependencies of absorption and fluorescence wavelengths on He...
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In: Physical Review A, 2008, vol. 77, no. 12, p. 012502
We give a detailed account on our semiempirical calculations of the forbidden electric tensor polarizability α₂⁽³⁾ of the ground state of free Cs atoms and of Cs atoms implanted in a solid 4He matrix. The results are compared with measurements of α₂⁽³⁾ in the free atoms [Europhys. Lett. 76, 1074 (2006)] and in He-trapped atoms [Phys. Rev. A 75, 042505 (2007)]. Features with...
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In: The European Physical Journal D, 2008, vol. 46, no. 1, p. 9-14
We present the first experimental study of time-resolved fluorescence from laser-excited Cs(6P1/2) atoms isolated in a solid ⁴He matrix. The results are compared to the predictions of the bubble model including the interaction of the atomic dipole with its radiation reflected at the bubble interface. Our results show that in liquid He as well as in the body-centered cubic (bcc)...
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In: Journal of Low Temperature Physics, 2011, vol. 165, no. 3-4, p. 166-176
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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 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: 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: Journal of Low Temperature Physics, 2011, vol. 165, no. 3-4, p. 166-176
Laser ablation of metals in liquid helium results in the formation of metal filaments with diameters on the order of 2–10 nanometres and of spherical nanoparticles. In superfluid helium these nanowires aggregate into centimeter-sized networks. We study the morphology and the electric conductivity of these large aggregates, as well as extinction spectra and the crystalline structure of the...
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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...
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