An investigation of positron trapping in indium

Crisp, V.H.C.; Lock, Duncan; West, R N

doi:10.1088/0305-4608/4/6/011

Cited by 30 publications

(5 citation statements)

References 17 publications

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“…These results show that the bulk S parameter (S M ) is sensitive to whether positrons are freely diffusing or in a trapped state and are consistent with previous Doppler broadening [9][10][11]15,55 and lifetime experiments. 12,13,44,56 An appreciable change is observed in S M at the melting point. Metals that do not trap positrons in the solid phase ͑Ga, Bi, Na, Sn͒ show a large increase in S M upon melting; we interpret this effect as due to the creation of centers that can trap positrons in the liquid phase.…”

Section: Discussionmentioning

confidence: 99%

“…13 This decrease is much faster than the decrease in metals with no vacancy trapping ͑Ga, Bi, or Sn͒ in the solid phase. Close to the melting point, the diffusion length is L ϩ Ϸ245(20) Å ͑Fig.…”

Section: Measurements Of Diffusion Length In Ga Bi Sn and Namentioning

confidence: 95%

“…An early study 7 of lifetime in solid In revealed an increase from Ϸ200 ps at 25°C, to 250 ps at 150°C ͑just below the melting point͒. Crisp et al 13 found that the bulk lifetime in In was b ϭ182 ps. Close to the melting point, they found a vacancy lifetime of v ϭ240 ps.…”

Section: Measurements Of S and F For Pb And In As A Function Of Tempementioning

confidence: 99%

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Positron diffusion in solid and liquid metals

et al. 1999

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We made a systematic study of the diffusion of positrons in several liquid and solid metals with a vertical positron beam. Several interesting effects have been observed by studying the line shape parameter S, the fraction of positronium formed at the surface, and the diffusion length of positrons in liquids. The S parameter and the fraction of positronium created and released at the surface ͑F parameter͒ were measured as a function of temperature in the solid and liquid phases of Ga, Bi, Na, Sn, In, and Pb. An appreciable change just below or across the melting point in the S parameter was measured in metals where positron trapping has not been observed ͑Ga, Bi, and Sn͒. In metals where positron trapping occurs in the solid phase, there is a small change or none in the S parameter ͑Pb and In͒, which indicates that there is only a small change in the nature of the traps. Positron trapping was seen in all the liquid metals, indicating that they have a high density of defectlike sites that trap positrons. The diffusion length of positrons in the liquid was extracted from the experimental data. In Ga, Bi, and Sn, there is a large drop in the diffusion length upon melting; in Pb and In, only a small change or none is seen. In all liquid metals the diffusion length increases as the temperature increases, suggesting that diffusion is related to trapping in temporary fluctuations in the liquid's structure. The positron moves from fluctuation to fluctuation. The size of the traps strongly depends on temperature, and so when it increases, the positron's hopping motion increases. We also measured the reemitted energy spectra of positrons from liquid and solid surfaces. No appreciable change was seen with increasing temperature or when the metals melted.

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Section: Discussionmentioning

confidence: 99%

Section: Measurements Of Diffusion Length In Ga Bi Sn and Namentioning

confidence: 95%

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Positron diffusion in solid and liquid metals

et al. 1999

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“…Free energy density functional theories [7,8] provide self-trapping as solution of the ions in a given host liquid. The sensitivity of positrons to changes induced by melting has already been reported by the positron annihilation angular correlation [9][10][11] and lifetime [12,13] studies for liquids. Gramsh et al [14,15] have observed very different behavior of the diffusion length L + of positrons in liquid and solid metals.…”

Section: Introductionmentioning

confidence: 92%

Positron and Ion Migrations and the Attractive Interactions between like Ion Pairs in the Liquids: Based on Studies with Slow Positron Beam

Kanazawa

Sasaki

Yamada

et al. 2014

J. Phys.: Conf. Ser.

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Abstract. We have discussed positron and ion diffusions in liquids by using the gaugeinvariant effection Lagrange density with the spontaneously broken density (the hedgehog-like density) with the internal non-linear gauge fields (Yaug-Mills gauge fields), and have presented the relation to the Hubbard-Onsager theory. IntroductionThe Investigation for ion mobility in the liquid phase has been one of the central area of physical chemistry. The electrohydrodynamic theory by Hubbard and Onsager [1,2] and the stochastic theory [3,4] for ionic conductivity in the liquid phase have been proposed.Since fluctuation from the equilibrium medium is preferable in liquid phase, localization of ions such as positrons is highly probable [5,6]. Free energy density functional theories [7,8] provide self-trapping as solution of the ions in a given host liquid. The sensitivity of positrons to changes induced by melting has already been reported by the positron annihilation angular correlation [9][10][11] and lifetime [12,13] studies for liquids. Gramsh et al. [14,15] have observed very different behavior of the diffusion length L + of positrons in liquid and solid metals. That is, on melting, L + decreases remarkably, and in the liquid phase, L + increases with temperature. Kanazawa [16][17][18][19][20] has introduced the effective Lagrangian in the gauge-invariant formula with spontaneous symmetry breaking for liquids and glasses, and has discussed the origin of the boson peak, the glass transition, and the viscosity of the supercooled liquids. Kanazawa and coworkers [21][22][23][24] proposed a qualitative explanation for the increase of the positron diffusion length L + with temperature in the liquid phase, by using the theoretical formula, which is based on the gaugeinvariant effective Lagrangian with spontaneously broken density (the hedgehog like fluctuation) and the massive internal gauge fields. In addition Kanazawa et al. [28] have suggested one origin of the attractive interaction between like ion pairs in liquids, extending the theoretical formula [20][21][22][23]. Recently Yamada et al. [29] have explained the origin of the attractive interaction between the Cl − -Cl − pair in water, which is introduced by the integral equation method [1], by using the theoretical formula [28]. In this study, we have analyzed the positron diffusion in the solid and liquid Pb, and have discussed the relation to the Hubbard-Onsager's dielectric theory for positrons and ions migrations in liquids.

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“…A technique using metal specimens containing positron source isotopes as bulk impurities is presented in this paper. 1.2. -Data on positron annihilation near thermally generated vacancies in metals are conventionally analysed by a trapping model which is generally recognized to contain questionable approximations and too many adjustable parameters [ 15], [16] ;…”

Section: Classificationmentioning

confidence: 99%

A new way of using positron-lifetime measurements to study lattice defects

Janot¹,

George²,

Boidron

1979

J. Phys. France

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

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An investigation of positron trapping in indium

Cited by 30 publications

References 17 publications

Positron diffusion in solid and liquid metals

Positron diffusion in solid and liquid metals

Positron and Ion Migrations and the Attractive Interactions between like Ion Pairs in the Liquids: Based on Studies with Slow Positron Beam

A new way of using positron-lifetime measurements to study lattice defects

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