NMR studies of the orientational ordering in dilute solid N2-Ar mixtures

Hamida, J. A.; Genio, E. B.; Sullivan, N. S.

doi:10.1007/bf00754657

Cited by 18 publications

(13 citation statements)

References 22 publications

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“…One of the best studied orientational glass systems is the N 2 -Ar mixture [37]. Pure N 2 has two low-pressure crystalline forms, the hexagonal closepacked (hcp) high temperature phase and the cubic Pa3 (fcc) low temperature phase.…”

Section: Electron Localization In a Disordered Insulating Hostmentioning

confidence: 99%

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Excess electron transport in cryoobjects

Eshchenko

Storchak

Brewer

et al. 2003

Low Temperature Physics

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Experimental results on excess electron transport in solid and liquid phases of Ne, Ar, and solid N 2 -Ar mixture are presented and compared with those for He. Muon spin relaxation technique in frequently switching electric fields was used to study the phenomenon of delayed muonium formation: excess electrons liberated in the m + ionization track converge upon the positive muons and form Mu (m + e -) atoms. This process is shown to be crucially dependent upon the electron's interaction with its environment (i.e., whether it occupies the conduction band or becomes localized in a bubble of tens of angstroms in radius) and upon its mobility in these states. The characteristic lengths involved are 10 -6 -10 -4 cm, the characteristic times range from nanoseconds to tens microseconds. Such a microscopic length scale sometimes enables the electron spend its entire free lifetime in a state which may not be detected by conventional macroscopic techniques. The electron transport processes are compared in: liquid and solid helium (where electron is localized in buble); liquid and solid neon (where electrons are delocalized in solid and the coexistence of localized and delocalized electrons states was found in liquid recently); liquid and solid argon (where electrons are delocalized in both phases); orientational glass systems (solid N 2 -Ar mixtures), where our results suggest that electrons are localized in orientational glass. This scaling from light to heavy rare gases enables us to reveal new features of excess electron localization on microscopic scale. Analysis of the experimental data makes it possible to formulate the following tendency of the muon end-of-track structure in condensed rare gases. The muon-self track interaction changes from the isolated pair (muon plus the nearest track electron) in helium to multi-pair (muon in the vicinity of tens track electrons and positive ions) in argon.

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Section: Electron Localization In a Disordered Insulating Hostmentioning

confidence: 99%

“…Above the critical Ar concentration x c » 0.23, the hcp lattice appears to be stable down to T = 0. The dynamical orientational disorder of the high-T phase eventually freezes into a static pattern of randomly oriented N 2 molecules, the orientational glass [37].…”

Section: Electron Localization In a Disordered Insulating Hostmentioning

confidence: 99%

Excess electron transport in cryoobjects

Eshchenko

Storchak

Brewer

et al. 2003

Low Temperature Physics

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“…The solid N 2 -Ar mixtures at low concentrations (Phase II of Figure 3b) therefore provide a better testbed for understanding quadrupolar or orientational glass formation. [38]. Copyright Springer Nature, 1998.…”

Section: Orientational and Quadrupolar Glasses: Basicsmentioning

confidence: 99%

Orientational Glasses: NMR and Electric Susceptibility Studies

et al. 2017

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Abstract:We review the results of a wide range of nuclear magnetic resonance (NMR) measurements of the local order parameters and the molecular dynamics of solid ortho-para hydrogen mixtures and solid nitrogen-argon mixtures that form novel molecular orientational glass states at low temperatures. From the NMR measurements, the distribution of the order parameters can be deduced and, in terms of simple models, used to analyze the thermodynamic measurements of the heat capacities of these systems. In addition, studies of the dielectric susceptibilities of the nitrogen-argon mixtures are reviewed in terms of replica symmetry breaking analogous to that observed for spin glass states. It is shown that this wide set of experimental results is consistent with orientation or quadrupolar glass ordering of the orientational degrees of freedom.

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“…One of the best studied orientational glass systems is the N 2 -Ar mixture [45]. Pure N 2 has two low-pressure crystalline forms, the hexagonal close-packed (hcp) high temperature phase and the cubic Pa3 (fcc) low temperature phase.…”

Section: Electron Localization In Orientational Glassmentioning

confidence: 99%

“…K; the high temperature b-phase is orientationally disordered. freezes into a static pattern of randomly oriented N 2 molecules, the orientational glass [45]. Being a mixture of insulators, the N 2 -Ar system has a very large energy gap (~10 eV), so that even at high temperature the ambient density of free electronic states is exponentially low.…”

Section: Electron Localization In Orientational Glassmentioning

confidence: 99%