Phonon spectroscopy in solid helium using x-rays

Seyfert, C.; Arms, D. A.; Sinn, H.; Simmons, R. O.; Burkel, E.

doi:10.1007/bf02569651

Cited by 8 publications

(5 citation statements)

References 3 publications

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“…The experiments (Burkel et al 1995, Schell et al 1996, Seyfert et al 1996, Seyfert 1998 were performed on single crystals in the hcp phase for both isotopes at a density of 13.25 cm 3 mol −1 . Due to the high zero-point energy, helium can only be solidified under pressure even at the lowest temperatures.…”

Section: Phonons In Hementioning

confidence: 99%

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Determination of phonon dispersion curves by means of inelastic x-ray scattering

Burkel¹

2001

J. Phys.: Condens. Matter

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Section: Phonons In Hementioning

confidence: 99%

“…The data were taken with energy resolutions of 5.9 meV and 8.6 meV, respectively. Solid lines are fits to the data (Seyfert 1998).…”

Section: Phonons In Hementioning

confidence: 99%

Determination of phonon dispersion curves by means of inelastic x-ray scattering

Burkel¹

2001

J. Phys.: Condens. Matter

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“…This is in per-fect agreement with the experimental results. [26][27][28][29][30] Our computations however show that the bcc structure is not quantum mechanically stable due to the non-zero number of negative modes obtained with the RHF/6-31G** method for all values of R. This instability is probably due to the surface effects, and interaction of neighboring clusters in a sufficiently large cluster may reduce this instability.…”

Section: -D Helium Clusters With Bcc Unit Cellsmentioning

confidence: 92%

A Computational Study of 3‐D Helium Clusters

Sabzyan

Zanjanchi

2007

J Chinese Chemical Soc

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Physical and thermodynamic properties have been calculated and analyzed for the best and optimized geometries of the 3-D clusters with N = 3 to N = 10 atoms and unit cells of three types of crystalline systems using ab initio RHF/6-31G** method. Dependence of the lattice binding energy on the cluster parameter, R, has been studied. Similar behavior observed for the binding energies for all clusters shows that probabilities of their existence in the condensed phase are more or less the same. In the next step, thermodynamic properties have been calculated and analyzed for He 27 3-D helium clusters with simple cubic, body centered cubic (bcc), trigonal and hexagonal (hcp) configurations. The results show that the hexagonal cluster is more favored over other clusters. It is found that these clusters are electronically stable over a limited range of the values for the lattice parameter. D f H is constant in this stability region and thus the D f G exactly follows the variations of TD f S. Surface effects have been investigated by comparing the square and hexagonal He 9 2-D lattices with the cubic and hexagonal He 27 3-D lattices, respectively. The lattice parameters, densities and molar volumes calculated for the clusters with hcp and bcc configurations have satisfactory agreement with the available experimental values. Properties of the He 13 , He 34 and He 104 hcp clusters have also been calculated and analyzed.

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“…The arrows at √ 4/3 = 1.155 indicate the classical ratio expected from the mass difference alone. The weighted average is 1.11 (5). For comparison, the triangles give values obtained by Debye temperature measurements (T, from [23]) and from Raman scattering (R, from [24]).…”

Section: The 3 He-to-4 He Phonon Frequency Ratiomentioning

confidence: 99%

“…The third-generation synchrotron ESRF in Grenoble allowed studies to be carried out with much higher accuracy. Preliminary data on the phonon dispersion relation for hcp 3 He and 4 He have already been published elsewhere [5,6].…”

Section: Introductionmentioning

confidence: 99%

Study of the lattice dynamics of hexagonal close-packed³He and⁴He using inelastic x-ray scattering

Seyfert

Simmons

Sinn

et al. 1999

J. Phys.: Condens. Matter

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We present the first measurement of the coherent dynamic structure factor S(Q, ω) of solid 3 He. At a density of 13.25(10) cm 3 mol −1 , we observed longitudinal phonons, using high-resolution inelastic x-ray scattering at momentum transfers 6 nm −1 < |Q| < 23 nm −1 . Their dispersion relation was determined along the c-axis in single crystals of hcp 3 He, and the spectra were described with a single-phonon model. For comparison, hcp 4 He at the same density was studied with the same technique. The comparison, including all available 4 He data from neutron scattering experiments, results in a phonon frequency ratio ω 3 /ω 4 of 1.11(5). Special attention is given to the scattering contribution due to multi-phonon excitations.

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Phonon spectroscopy in solid helium using x-rays

Cited by 8 publications

References 3 publications

Determination of phonon dispersion curves by means of inelastic x-ray scattering

Determination of phonon dispersion curves by means of inelastic x-ray scattering

A Computational Study of 3‐D Helium Clusters

Study of the lattice dynamics of hexagonal close-packed³He and⁴He using inelastic x-ray scattering

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Phonon spectroscopy in solid helium using x-rays

Cited by 8 publications

References 3 publications

Determination of phonon dispersion curves by means of inelastic x-ray scattering

Determination of phonon dispersion curves by means of inelastic x-ray scattering

A Computational Study of 3‐D Helium Clusters

Study of the lattice dynamics of hexagonal close-packed3He and4He using inelastic x-ray scattering

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Resources

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Study of the lattice dynamics of hexagonal close-packed³He and⁴He using inelastic x-ray scattering