Lifetime of the Cs 6P1/2 state in bcc and hcp solid 4He

Hofer, Adrian; Moroshkin, Peter; Ulzega, Simone; Weis, A.

doi:10.1140/epjd/e2007-00275-5

Cited by 6 publications

(8 citation statements)

References 18 publications

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“…For time-resolved measurements two modifications of the same setup were used. The lifetime of the atomic 6P 1/2 state of Cs was studied [134] using a time-resolved single photon counting technique. Radiation from a pulsed diode laser at 850 nm (10 kHz repetition rate) excited the implanted atoms and a single-photon counting photomultiplier (PM) detected the light analyzed by the spectrograph.…”

Section: Setup For Optical Spectroscopy and Time-resolved Studiesmentioning

confidence: 99%

“…An experimental study of the Cs 6P 1/2 lifetime in solid He has been presented in [134]. In that study a time-correlated photon counting technique was used and the data were taken both in bcc and hcp solid He matrices.…”

Section: Hydrogen and Alkali Dimersmentioning

confidence: 99%

“…The difference between the lifetime of the free Cs atom and a Cs atom embedded in a He matrix is mostly due to the so-called cavity effect [181,134]. The electromagnetic radiation of the atomic dipole in the bubble is partially reflected at the bubble interface and interacts with the dipole.…”

Section: Hydrogen and Alkali Dimersmentioning

confidence: 99%

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Atomic and molecular defects in solid 4He

2008

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Section: Setup For Optical Spectroscopy and Time-resolved Studiesmentioning

confidence: 99%

Section: Hydrogen and Alkali Dimersmentioning

confidence: 99%

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Atomic and molecular defects in solid 4He

2008

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“…where Ω is the solid angle of the collected light (0.12 sr), κ is the transmission efficiency of the detection beam estimated to be 0.38 at 880 nm, η is the fluorescence efficiency for the D1 line measured to be 0.9 at 25 bar (26). This formula takes into account the fact that the waist of Ti:Sa beam in the cell (0.3 mm) is smaller than the diameter of the area seen by the APD detector (l det = 1.1 mm).…”

Section: Estimate Of the Atomic Densitymentioning

confidence: 99%

Efficient atomization of cesium metal in solid helium by low energy (10 $μ$J) femtosecond pulses

Melich,

Dupont-Roc,

Jacquier

2009

Preprint

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Metal atoms in solid and liquid helium-4 have attracted some interest either as a way to keep the atoms in a weakly perturbing matrix, or using them as a probe for the helium host medium. Laser sputtering with nanosecond pulsed lasers is the most often used method for atom production, resulting however in a substantial perturbation of the matrix. We show that a much weaker perturbation can be obtained by using femtosecond laser pulses with energy as low as 10 µJ. As an unexpected benefit, the atomic density produced is much higher.

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“…The atomicbubble energetics are illustrated in fig. 1 by a potential diagram derived in [13] for a Cs atom in condensed He. The bubble shape and size are determined by the dopant's electron density distribution that differs significantly for the excited and ground states.…”

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Phonon generation in condensed ⁴ He by laser-excited atomic bubbles

Moroshkin

Lebedev

Weis

2011

EPL

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-We discuss the interaction between nanometer-sized defects (atomic bubbles) and elementary excitations (phonons) in quantum fluids and solids. We observe that optical excitations in embedded metal atoms induce bubble expansions/contractions that create strongly localized phonon wave packets in the quantum matrix. We derive the structure and dynamics of these vibronic excitations from the experimental laser-induced fluorescence spectra of Au and Cu atoms in liquid and solid He. The atomic vibrations are found to be strongly damped on the 50Å and 5 ps scales in agreement with pure hydrodynamic estimations.The dynamics of quantum fluids and solids is described in terms of quantized elementary excitations (such as, e.g., phonons and rotons in HeII [1]) with energies E and momenta k of meV range (tens of K) and a fewÅ −1 , respectively. The most widely used method for probing these excitations is the inelastic scattering of neutrons having comparable energies and momenta. Each scattering event creates one phonon (roton), whose parameters E and k can be determined from the energy and momentum of the scattered neutron. First neutron scattering experiments on superfluid helium were reported in the 1950s, and nowadays the technique is still widely used, in particular in connection with excitations in thin helium films [2], helium confined in nanoporous media [3], and possible manifestations of supersolidity [4]. Scattering experiments can also be performed with optical photons [5] (E 2.5 eV, k 10 −4Å−1 ). However, the smallness of the photon momentum implies that only k ≈ 0 optical phonons (which exist only in solids) or pairs of counterpropagating excitations can be created.Impurity atoms and molecules represent another class of nanoscopic objects that may create elementary excitations in condensed helium [6][7][8][9][10]. However, their potential for probing the dynamics of quantum fluids and solids at the microscopic level has not been exploited in depth so far. The main advantage of atomic dopants over other (a) E-mail: peter.moroshkin@unifr.ch probes is that they can be interrogated by means of laser radiation. Therefore, a variety of laser-spectroscopic and time-resolved methods can be applied for obtaining information on the matrix excitations. The mechanism of impurity-phonon interactions at the microscopic scale is not quantitatively understood at present. In particular, it is not clear how the presence of dopants modifies the spectrum and dispersion relation of the excitations in the helium sample, e.g., via the appearance of localized modes which do not exist in pure condensed helium.Here we present a simple hydrodynamic model for describing the dynamics of a vibrating atomic bubble. Our analysis reveals two regimes of the impurity-phonon interaction which we shall refer to as quasiclassical and quantum. We analyze existing optical data of impurity atoms in condensed helium and present a new laser-spectroscopic study of condensed 4 He doped with the transition-metal atoms Au and Cu. Our results demon...

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Lifetime of the Cs 6P1/2 state in bcc and hcp solid 4He

Cited by 6 publications

References 18 publications

Atomic and molecular defects in solid 4He

Atomic and molecular defects in solid 4He

Efficient atomization of cesium metal in solid helium by low energy (10 $μ$J) femtosecond pulses

Phonon generation in condensed ⁴ He by laser-excited atomic bubbles

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Lifetime of the Cs 6P1/2 state in bcc and hcp solid 4He

Cited by 6 publications

References 18 publications

Atomic and molecular defects in solid 4He

Atomic and molecular defects in solid 4He

Efficient atomization of cesium metal in solid helium by low energy (10 $μ$J) femtosecond pulses

Phonon generation in condensed 4 He by laser-excited atomic bubbles

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Phonon generation in condensed ⁴ He by laser-excited atomic bubbles