Electrons and positrons in dense gases

Khrapak, Aleksei G.; Yakubov, I. T.

doi:10.1070/pu1979v022n09abeh005607

Cited by 64 publications

(21 citation statements)

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“…Their final conclusions [5][6][7] practically coincide with the intuitively expected picture: the electron cluster should exist, and the electron localization degree as well as the cluster mass should monotonously grow with the density media and polarizability demonstrating exponential sensitivity to the temperature. The outlined approach [5][6][7] reveals no hints of electron mobility growth with the medium density [2][3][4].In the present paper we show that in gaseous media with negative values of a 0 it is possible for electron, in a ceratin range of gas densities and temperatures, to form an autolocalized state involving formation of a cluster with the characteristic length l >> a B (where a B is the Bohr radius) if the electron-gas interaction V n 0 ( ) is treated beyond the linear approximation as in Eq. (1).…”

supporting

confidence: 53%

supporting

confidence: 53%

“…The existing description [5][6][7] of electron clusters in cryogenic media with negative scattering lengths a 0 employs the well-known approximation [8,9] for electron-medium interaction energy which is linear in the gas density n. Within this approximation, the minimal energy V 0 of delocalized electron injected into the gaseous media is calculated as …”

mentioning

confidence: 99%

“…Although there are some indications of the existence of electron clusters in xenon [1], they are not observed on the expected scale in media with comparatively high atomic polarizabilities (krypton, xenon) which are presumably likely to develop various electron autolocalization phenomena. On the contrary, the data on electron mobility in Ar, Kr, and Xe [2-4] reveal that electrons remain practically free (compared to mobility of positive ions possessing the structure of massive polaronic-type formations) in their motion, at least in the vicinity of the characteristic electron mobility peak which is observed for all heavy inert gases.The existing description [5][6][7] of electron clusters in cryogenic media with negative scattering lengths a 0 employs the well-known approximation [8,9] for electron-medium interaction energy which is linear in the gas density n. Within this approximation, the minimal energy V 0 of delocalized electron injected into the gaseous media is calculated aswhere m is the free electron mass. In terms of electron energy bands in solids, V 0 is the conduction band bottom energy.…”

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Localized electrons in dense heavy noble gases

Nazin

Shikin

2009

Low Temperature Physics

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The paper addresses counterintuitive behavior of electrons injected into dense cryogenic media with negative scattering length a 0 . Instead of expected polaronic effect (formation of density enhancement clusters) which should substantially reduce the electron mobility, an opposite picture is observed: with increasing | | a 0 (the trend taking place for inert gases with the growth of atomic number) and the medium density, the electrons remain practically free. An explanation of this behavior is provided based on consistent accounting for the non-linearity of electron interaction with the gaseous medium in the gas atom number density.PACS: 71.10.-w Theories and models of many-electron systems.Keywords: delocalized electron, heavy inert gases, negativ scattering length.One of the most interesting and still important issues in physics of cryogenic media is the problem of electron clusters which emerged almost simultaneously with that of electron bubbles. However, it is much less transparent (compared to the case of electron bubbles) from the experimental side. Although there are some indications of the existence of electron clusters in xenon [1], they are not observed on the expected scale in media with comparatively high atomic polarizabilities (krypton, xenon) which are presumably likely to develop various electron autolocalization phenomena. On the contrary, the data on electron mobility in Ar, Kr, and Xe [2-4] reveal that electrons remain practically free (compared to mobility of positive ions possessing the structure of massive polaronic-type formations) in their motion, at least in the vicinity of the characteristic electron mobility peak which is observed for all heavy inert gases.The existing description [5][6][7] of electron clusters in cryogenic media with negative scattering lengths a 0 employs the well-known approximation [8,9] for electron-medium interaction energy which is linear in the gas density n. Within this approximation, the minimal energy V 0 of delocalized electron injected into the gaseous media is calculated aswhere m is the free electron mass. In terms of electron energy bands in solids, V 0 is the conduction band bottom energy. The case of a 0 0 > corresponds to formation a single-electron bubble. On the other hand, a density enhancement domain with higher gas atom concentration (i.e., a cluster) may develop around the electron if a 0 0 < . The authors of Refs. 5-7 made every effort to provide a quantitatively accurate description of the gas density around the localized electron in the linear approximation. In addition to (1), they also introduced a non-local electron-gas interaction of the typewhere y( ) r is the electron wave function, took into account the deviation of the gas entropy contribution to the total free energy from the ideal gas, etc. Their final conclusions [5][6][7] practically coincide with the intuitively expected picture: the electron cluster should exist, and the electron localization degree as well as the cluster mass should monotonously grow with the density media a...

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supporting

confidence: 53%

supporting

confidence: 53%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Localized electrons in dense heavy noble gases

Nazin

Shikin

2009

Low Temperature Physics

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“…The observed mobility is then a weighted sum of the contribution of the mobilities of the two states [14,32]. For the bubble state the semihydrodynamic mobility…”

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confidence: 99%

High temperature electron localization in dense He gas

Borghesani

DeRiva²,

Santini³

2002

IEEE Trans. Dielect. Electr. Insul.

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We report new accurate mesasurements of the mobility of excess electrons in high density Helium gas in extended ranges of temperature [(26 ≤ T ≤ 77) K] and density [(0.05 ≤ N ≤ 12.0) atoms · nm −3 ] to ascertain the effect of temperature on the formation and dynamics of localized electron states. The main result of the experiment is that the formation of localized states essentially depends on the relative balance of fluid dilation energy, repulsive electron-atom interaction energy, and thermal energy. As a consequence, the onset of localization depends on the medium disorder through gas temperature and density. It appears that the transition from delocalized to localized states shifts to larger densities as the temperature is increased. This behavior can be understood in terms of a simple model of electron self-trapping in a spherically symmetric square well.

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Electron Localization and Electron Induced Cluster Formation in Dense Polar Vapors

Krebs

1984

Ber Bunsenges Phys Chem

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We discuss the mobilities of electrons photoinjected in dense sub‐ and supercritical polar vapors (NH3, H2O) as a function of vapor density and temperature. With increasing density they show a transition from the quasi‐free to the localized electron state. The density range where the onset of this transition is observed obeys the Ioffe‐Regel principle. At this density large radius orientational fluctuations of the dipole molecules as precursors of dense clusters are important for electron localization. Electron cluster formation is strongly supported by the observed temperature dependence of the electron mobility in low density H2O vapor. These results are discussed in context with optical absorption measurements on excess electrons in sub‐ and supercritical D2O and ND3. In NH3 gas around the critical density the electron mobility shows an anomalous density dependence. It is concluded that there occurs a further transition: the electron localized in a dense orientational cluster obviously turns over to an electron localized in a cavity (solvated electron).

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Electrons and positrons in dense gases

Cited by 64 publications

References 2 publications

Localized electrons in dense heavy noble gases

Localized electrons in dense heavy noble gases

High temperature electron localization in dense He gas

Electron Localization and Electron Induced Cluster Formation in Dense Polar Vapors

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