Temperature dependence of the positron annihilation lifetime in single-crystal YBa2Cu3O7

1988 ◽  
Vol 38 (1) ◽  
pp. 848-851 ◽  
Author(s):  
D. R. Harshman ◽  
L. F. Schneemeyer ◽  
J. V. Waszczak ◽  
Y. C. Jean ◽  
M. J. Fluss ◽  
...  
Keyword(s):  
Single Crystal ◽  
Temperature Dependence ◽  
Positron Annihilation ◽  
Positron Annihilation Lifetime

Positronium Lifetime Study on Subnanoscopic Structure of Polyrotaxane

2012 ◽  
Vol 733 ◽  
pp. 167-170
Author(s):  
K. Ito ◽  
Chang Ming Zhao ◽  
Kohzo Ito ◽  
Yoshinori Kobayashi
Keyword(s):  
Ethylene Glycol ◽  
Temperature Dependence ◽  
Positron Annihilation ◽  
Chemical Structure ◽  
Poly Ethylene Glycol ◽  
Positron Annihilation Lifetime ◽  
Positronium Lifetime ◽  
End Groups ◽  
Poly Ethylene ◽  
Free Volume Hole

The subnanoscopic structures of polyrotaxanes, prepared from α-cyclodextrins, poly(ethylene glycol), and bulky adamantane end groups, were examined by means of the positron annihilation lifetime technique, in consideration of the free-volume hole, quantified from the long-lived ortho-positronium (o-Ps) lifetimes. The influence of the chemical structure on the temperature dependence of the o-Ps lifetimes are discussed.

Characterisation of Defects in ZnO Implanted by Hydrogen

2015 ◽  
Vol 365 ◽  
pp. 49-54
Author(s):  
Ivan Procházka ◽  
Jakub Čížek ◽  
Jan Valenta ◽  
Vladimír Havránek ◽  
Petr Hruška ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Positron Annihilation ◽  
Optical Activity ◽  
Optical Transmittance ◽  
Hydrogen Impurity ◽  
High Quality ◽  
Positron Annihilation Lifetime ◽  
Zno Single Crystal

In the present work, defects created by implantation of hydrothermally grown ZnO single crystals of high quality with H+ions were investigated by positron annihilation lifetime (LT) spectroscopy combined with measurements of optical transmittance (OT) and photoluminescence (PL). First, zinc vacancies attached with one hydrogen impurity (VZn– 1H) atom were identified in the virgin ZnO single crystal. The ZnO single crystals were then bombarded by H+ions with the energy of 2.5 MeV to the fluence of 1016cm-2. It was found that VZn– VOdivacancies were introduced into ZnO by H+-implantation. Effects of H+-implantation on the optical activity of defects in ZnO lattice are characterised in the light of the present OT and PL data.

Positronium Molecule Formation on Al (111)a

2008 ◽  
Vol 607 ◽  
pp. 22-24
Author(s):  
S.H.M. Deng ◽  
D.B. Cassidy ◽  
A.P. Mills
Keyword(s):  
Single Crystal ◽  
Positron Annihilation ◽  
Positron Beam ◽  
Single Shot ◽  
Beam Density ◽  
Positron Annihilation Lifetime ◽  
Molecule Formation ◽  
Positronium Lifetime ◽  
Positronium Molecule ◽  
Incident Positron

A single crystal Al (111) sample cleaned by repeated cycles of ion bombardment and annealing was irradiated by a subnanosecond high density positron beam [1] and the resulting positronium lifetime spectra were measured using single shot positron annihilation lifetime spectroscopy (SSPALS) [2]. We observed the amount of positronium emitted dependence on the incident positron beam density, which indicates the formation of positronium molecules (Ps2) at the Al (111) surface [3]. The Ps2 formation probability appears to be extremely sensitive to surface contamination and further experiments under improved vacuum conditions are planned to clarify this effect.

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