Lattice dynamics and molecular rotations in solid hydrogen deuteride: Inelastic neutron scattering study

Colognesi, D.; Formisano, F.; Ramirez‐Cuesta, Anibal J.; Ulivi, Lorenzo

doi:10.1103/physrevb.79.144307

Cited by 8 publications

(6 citation statements)

References 45 publications

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“…In Fig. 2d , the INS spectrum shows an additional transition at 5.3 meV, corresponding to solid orthohydrogen 10 , 12 . This contribution is present in the INS spectra of bulk solid hydrogen at atmospheric pressure (Fig.…”

Section: Resultsmentioning

confidence: 95%

Rapid and efficient hydrogen clathrate hydrate formation in confined nanospace

Farrando-Pérez

Balderas‐Xicohténcatl

Cheng

et al. 2022

Nat Commun

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Clathrate hydrates are crystalline solids characterized by their ability to accommodate large quantities of guest molecules. Although CH4 and CO2 are the traditional guests found in natural systems, incorporating smaller molecules (e.g., H2) is challenging due to the need to apply higher pressures to stabilize the hydrogen-bonded network. Another critical limitation of hydrates is the slow nucleation and growth kinetics. Here, we show that specially designed activated carbon materials can surpass these obstacles by acting as nanoreactors promoting the nucleation and growth of H2 hydrates. The confinement effects in the inner cavities promote the massive growth of hydrogen hydrates at moderate temperatures, using pure water, with extremely fast kinetics and much lower pressures than the bulk system.

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Section: Resultsmentioning

confidence: 95%

Rapid and efficient hydrogen clathrate hydrate formation in confined nanospace

Farrando-Pérez

Balderas‐Xicohténcatl

Cheng

et al. 2022

Nat Commun

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“…This suggests that at temperatures higher than 5 K, solid D 2 can be treated as a classical system to the first order approximation. Many ongoing research [14,26] are looking for the evidence of quantum interference in H 2 , HD and possibly D 2 .…”

Section: Dynamics In Solid D2mentioning

confidence: 99%

Coherent Neutron Scattering in Polycrystalline Deuterium and its Implications for Ultracold Neutron Production

Lavelle¹,

Salvat²

2010

Preprint

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This paper presents a calculation of the neutron cross-sections in solid materials (used in practical neutron sources) with a large coherent scattering contribution. In particular, the dynamic structure function S(Q, ω) of polycrystalline ortho-D2 is evaluated using a Monte-Carlo calculation that performs an average over scattering angles relative to crystal axes in random orientations. This method uses an analytical dispersion function with force constants derived from neutron scattering data of single crystal D2 in the framework of an axially symmetric force tensor. The resulting two dimensional map of S(Q, ω) captures details of the phonon branches as well as the molecular rotations, that can be compared directly to data from inelastic neutron scattering on polycrystalline D2. This high resolution information is used to calculate the absolute cross-sections of production and upscattering loss of ultracold neutron (UCN). The resulting scattering cross-sections are significantly different, especially for UCN upscattering, from the previous predictions using the approach centered on the incoherent approximation.

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“…It is also quite surprising that the neutron response of HD, which anyway belongs to an important class of systems, escaped for decades a detailed treatment like those elegantly devised on homonuclear diatomic molecules by Young and Koppel (YK) [6] and by Sears [7] in the mid 1960s. Indeed, only much later the neutron cross section of HD has been briefly taken into consideration in the analysis of solid state data [8], and further years passed before a formal description of the heteronuclear diatomic case was tackled by the research group studying the behaviour of HD in the cages of clathrate hydrates [9,10]. However, like the papers by Sears on the homonuclear case [7], also these last works deal with the scattering of cold and thermal neutrons from a low-temperature sample, therefore vibrations are not excited and the developed formalism is rightly limited to the specific case under consideration, where rotations alone are excited and only zero-point vibrational effects must be retained.…”

Section: Introductionmentioning

confidence: 99%

“…In order to extend the applicability of the model also to the higher incident energies involved in applications, we therefore found it important to provide a more general treatment of heteronuclear diatomic fluids, including harmonic vibrations and overcoming the use of Debye-Waller factors [8], as formalised for the homonuclear case in Refs. [6,11] and like we did in Refs.…”

Section: Introductionmentioning

confidence: 99%

The neutron cross section of low-temperature heteronuclear diatomic fluids

Guarini

2021

Preprint

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The present work deals with the formal description of the response to neutrons of heteronuclear diatomic liquids, with special interest in the case of hydrogen deuteride as a possible candidate for the moderation process required in the production of cold neutrons. Preliminary evaluations of the model giving the neutron double differential cross section of a heteronuclear vibrating rotor are performed by using, as a first approximation, the ideal gas law for the centre-of-mass translational dynamics, which is expected to be appropriate at incident neutron energies above the thermal region. The unavailability of double differential cross section experimental data on liquid HD compels to test the model calculations only at an integral level, i.e. against the only measurement carried out on liquid HD for the determination of its neutron total cross section. The present findings indicate the evident need of more accurate measurements of the total cross section, as well as of future work devoted to double differential cross section determinations and appropriate simulations of the translational dynamics of this weakly quantum fluid.

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Lattice dynamics and molecular rotations in solid hydrogen deuteride: Inelastic neutron scattering study

Cited by 8 publications

References 45 publications

Rapid and efficient hydrogen clathrate hydrate formation in confined nanospace

Rapid and efficient hydrogen clathrate hydrate formation in confined nanospace

Coherent Neutron Scattering in Polycrystalline Deuterium and its Implications for Ultracold Neutron Production

The neutron cross section of low-temperature heteronuclear diatomic fluids

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