Temperature Dependent Electron Acceptor Properties of Zeolite Y: a Combined Mössbauer and Positron Lifetime Spectroscopy Study

2001 ◽  
Vol 363-365 ◽  
pp. 266-268 ◽  
Author(s):  
Károly Süvegh ◽  
György Vankó ◽  
Attila Domján ◽  
Attila Vértes
Keyword(s):  
Electron Acceptor ◽  
Positron Lifetime ◽  
Zeolite Y ◽  
Spectroscopy Study ◽  
Temperature Dependent ◽  
Positron Lifetime Spectroscopy

STUDY OF MOLECULAR MOTIONS IN TWO LIQUID CRYSTAL FORMING COMPOUNDS EMPLOYING PLS

2006 ◽  
Vol 20 (14) ◽  
pp. 2019-2034 ◽  
Author(s):  
K. CHANDRAMANI SINGH ◽  
M. SHARMA ◽  
P. C. JAIN
Keyword(s):  
Liquid Crystal ◽  
Temperature Dependence ◽  
Liquid Crystalline ◽  
Positron Lifetime ◽  
Strong Temperature Dependence ◽  
Molecular Motions ◽  
Temperature Dependent ◽  
Slow Cooling ◽  
Positron Lifetime Spectroscopy ◽  
Motion Studies

Results of molecular motion studies carried out in two liquid crystal forming compounds n-p-cyano-p-hexyloxybiphenyl (M18) and n-p-ethoxybenzylidene-p-butylaniline (EBBA) using positron lifetime spectroscopy (PLS) are presented. Temperature dependent positron lifetime measurements have been performed in each compound during the heating cycle of samples prepared by either quenching or slow cooling from the respective liquid crystalline phase of the compounds. In both the compounds, behaviors of the quenched and slow cooled samples are found to be different. The material in the quenched sample, unlike the slow-cooled sample, exhibits strong temperature dependence before it undergoes a glass transition. In each case, the temperature dependence of o-Ps pick-off lifetime in the quenched sample shows broad peaks at various characteristic temperatures. These peaks have been attributed to various intra- and inter-molecular motions associated with these compounds. The characteristic frequencies of some of the modes observed in the present work agree well with the literature reported values obtained from FIR and Raman studies. The present study demonstrates the usefulness of PLS in the study of molecular motions.

scholarly journals Synchrotron VUV-UV and positron lifetime spectroscopy study of vacancy-type defects in reactor neutron-irradiated MgO��nAl2O3 (n = 2)

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Abu Zayed Mohammad Saliqur Rahman ◽  
Xingzhong Cao ◽  
Baoyi Wang ◽  
Jarah Evslin ◽  
Qiu Xu ◽  
...  
Keyword(s):  
Positron Lifetime ◽  
Reactor Neutron ◽  
Spectroscopy Study ◽  
Positron Lifetime Spectroscopy

Positron Lifetime Spectroscopy Study of γ-Irradiated Epoxy Resin: Dose and Time Dependent Measurements

1992 ◽  
Vol 105-110 ◽  
pp. 1729-1732 ◽  
Author(s):  
Károly Süvegh ◽  
F. Ranogajec ◽  
M. Komor-Ranogajec ◽  
E. Tálas ◽  
M. Ovári ◽  
...  
Keyword(s):  
Epoxy Resin ◽  
Positron Lifetime ◽  
Time Dependent ◽  
Spectroscopy Study ◽  
Positron Lifetime Spectroscopy

scholarly journals Undoped gallium antimonide studied by positron annihilation spectroscopy

2003 ◽  
Vol 799 ◽  
Author(s):  
S. K. Ma ◽  
C. C. Ling ◽  
H. M. Weng ◽  
D. S. Hang
Keyword(s):  
Ionization Energy ◽  
Gallium Antimonide ◽  
Positron Lifetime ◽  
Positron Annihilation Spectroscopy ◽  
Lifetime Data ◽  
Temperature Dependent ◽  
Lifetime Component ◽  
Grown Sample ◽  
Related Defect ◽  
Positron Lifetime Spectroscopy

ABSTRACTPositron lifetime spectroscopy has been used to study the vacancy type defects in undoped gallium antimonide. Temperature dependent positron trapping into the VGa-related defect having a characteristic lifetime of 310ps was observed in the as-grown sample. The lifetime data were well described by a model involving the thermal ionization (0/-) of the VGa-related defect and its ionization energy was found to be E(0/-)=83meV. For the electron irradiated sample, the VGa-related defect with lifetime of 310ps that was found in the non-irradiated samples was also identified. Moreover, another lifetime component (280ps) was only observed in the electron irradiated sample but not in the non-irradiated sample. It was also attributed to the VGa-related defect. The two identified VGa-related defects should have different microstructures because of their difference in characteristic lifetimes. The 280ps component remains thermally stable after the 500°C annealing while the 310ps component anneals at 300°C.

TEMPERATURE-DEPENDENT STUDIES IN SOME HOMOLOGUES OF ALKYLOXY CYANOBIPHENYL EMPLOYING POSITRON LIFETIME SPECTROSCOPY

2000 ◽  
Vol 14 (18) ◽  
pp. 1927-1938 ◽  
Author(s):  
M. SHARMA ◽  
C. KAUR ◽  
K. CHANDRAMANI SINGH ◽  
P. C. JAIN
Keyword(s):  
Positron Annihilation ◽  
Nematic Phase ◽  
Structural Changes ◽  
Positron Lifetime ◽  
Temperature Dependent ◽  
Lifetime Measurements ◽  
Positron Lifetime Spectroscopy ◽  
Crystalline Polymorphism

Some homologues of alkyloxy cyanobipheny1 (6OCB, 8OCB, 9OCB, 10OCB) have been investigated by employing positron lifetime spectroscopy. In each of these compounds, temperature dependent positron lifetime measurements have been carried out, both in the heating as well as cooling cycles. Besides detecting many interesting features like solid-crystalline polymorphism, anti-parallel bimolecular association, formation of cybotactic groups in the nematic phase, positron annihilation parameters have been able to reveal anomalous structural changes taking place in these compounds.

Nanometer size pores in ionic liquid loaded silica gel characterized by positron lifetime spectroscopy

2015 ◽  
Vol 213 (1) ◽  
pp. 165-169 ◽  
Author(s):  
Christian Herold ◽  
Hubert Ceeh ◽  
Thomas Gigl ◽  
Markus Reiner ◽  
Marco Haumann ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Silica Gel ◽  
Positron Lifetime ◽  
Nanometer Size ◽  
Positron Lifetime Spectroscopy

Defects in electron irradiated GaP studied by positron lifetime spectroscopy

1995 ◽  
Vol 60 (6) ◽  
pp. 541-544 ◽  
Author(s):  
A. Polity ◽  
Th. Abgarjan ◽  
R. Krause-Rehberg
Keyword(s):  
Positron Lifetime ◽  
Positron Lifetime Spectroscopy

Study of Compensation Defects and Electron Irradiation-Induced Defects in Undoped SI-InP by Positron Lifetime Spectroscopy

2008 ◽  
Vol 607 ◽  
pp. 134-136
Author(s):  
Y.J. Zhang ◽  
Ai Hong Deng ◽  
You Wen Zhao ◽  
J. Yu ◽  
X.X. Yu ◽  
...  
Keyword(s):  
Electron Irradiation ◽  
Positron Lifetime ◽  
Deep Level ◽  
High Concentration ◽  
Positron Annihilation Lifetime ◽  
Donor Type ◽  
Positron Lifetime Spectroscopy ◽  
Transient Spectroscopy ◽  
Induced Defects ◽  
Irradiation Induced Defects

Positron annihilation lifetime (PAL) spectroscopy，photo-induced current transient spectroscopy (PICTS) and thermally stimulated current (TSC) have been employed to study the formation of compensation defects and their evolvement under iron phosphide (IP) ambience or pure phosphide (PP) ambience. In the formation of IP SI-InP, the diffusion of Fe atoms suppresses the formation of some open-volume defects. As to PP SI-InP, VInH4 complexes dissociate into acceptor vacancies VInHn(n-3)(n=0,1,2,3), which compensate residual donor type defects and make the sample semi-insulating. Electron irradiation-induced deep level defects have been studied by TSC in PP and IP SI-InP, respectively. In contrast to a high concentration of irradiation-induced defects in as-grown and PP annealed InP, IP SI-InP has a very low concentration of defects.

Sign in / Sign up

Export Citation Format

Share Document