Positron annihilation in methane

1977 ◽  
Vol 55 (3) ◽  
pp. 235-239 ◽  
Author(s):  
A. C. Mao ◽  
D. A. L. Paul
Keyword(s):  
Electric Field ◽  
Positron Annihilation ◽  
Applied Electric Field ◽  
Room Temperature ◽  
Positive Energy ◽  
Annihilation Rate ◽  
Linear Region ◽  
Gas Density ◽  
Single Level ◽  
Made In

Measurements of positron annihilation rates at room temperature under the influence of an applied electric field have been made in methane at different pressures. The experiments were all carried out in the linear region in which the annihilation rate is accurately proportional to gas density. We find Zeff = 142.7 ± 2.0 at 21 °C and zero electric field. At 1000 Torr Zeff decreases linearly with the electric field, the gradient being about 2.5 × 10−2 per (V cm−1 atm−1) at that temperature. The results repudiate the idea of a positive energy single level Breit–Wigner resonance as being responsible for the high value of Zeff, and in this sense are in agreement with the findings of McNutt, Summerour, Ray, and Huang.

Positron annihilation in methane gas

1970 ◽  
Vol 48 (24) ◽  
pp. 2984-2990 ◽  
Author(s):  
P. M. Smith ◽  
D. A. L. Paul
Keyword(s):  
Positron Annihilation ◽  
Standard Error ◽  
Room Temperature ◽  
Annihilation Rate ◽  
Effective Number ◽  
Gas Density ◽  
Methane Gas ◽  
Free Positron

The annihilation of positrons in methane gas at room temperature has been measured at pressures below 2 atm. The annihilation rate for the free positron component is proportional to the gas density and corresponds to an effective number of electrons per molecule taking part in annihilation, Zeff = 139.6 ± 1.0 (standard error). The quenching of orthopositronium corresponds to 1Zeff = 0.57 ± 0.07. Resonance annihilation is discussed in a general way.

scholarly journals Current-Induced Spin Photocurrent in GaAs at Room Temperature

Sensors ◽  
2022 ◽  
Vol 22 (1) ◽  
pp. 399
Author(s):  
Yang Zhang ◽  
Yu Liu ◽  
Xiao-Lan Xue ◽  
Xiao-Lin Zeng ◽  
Jing Wu ◽  
...  
Keyword(s):  
Electric Field ◽  
Spin Polarization ◽  
Applied Electric Field ◽  
Room Temperature ◽  
Polarization Direction ◽  
Applied Bias ◽  
Applied Bias Voltage ◽  
Sample Plane ◽  
Bulk Gaas ◽  
Circularly Polarized

Circularly polarized photocurrent, observed in p-doped bulk GaAs, varies nonlinearly with the applied bias voltage at room temperature. It has been explored that this phenomenon arises from the current-induced spin polarization in GaAs. In addition, we found that the current-induced spin polarization direction of p-doped bulk GaAs grown in the (001) direction lies in the sample plane and is perpendicular to the applied electric field, which is the same as that in GaAs quantum well. This research indicates that circularly polarized photocurrent is a new optical approach to investigate the current-induced spin polarization at room temperature.

Complex dependence of the positron annihilation rate on methane gas density and temperature

1975 ◽  
Vol 62 (5) ◽  
pp. 1777-1789 ◽  
Author(s):  
J. D. McNutt ◽  
V. B. Summerour ◽  
A. D. Ray ◽  
P. H. Huang ◽  
D. A. Johnson
Keyword(s):  
Positron Annihilation ◽  
Annihilation Rate ◽  
Gas Density ◽  
Methane Gas ◽  
Complex Dependence

Ferroelectricity and phase transitions in In2Se3 van der Waals material

Nanoscale ◽  
2020 ◽  
Vol 12 (44) ◽  
pp. 22688-22697
Author(s):  
Maryam Soleimani ◽  
Mahdi Pourfath
Keyword(s):  
Phase Transitions ◽  
Electric Field ◽  
Applied Electric Field ◽  
Room Temperature ◽  
Van Der Waals ◽  
Out Of Plane

Van der Waals layered α-In2Se3 has shown out-of-plane ferroelectricity down to the bilayer and monolayer thicknesses at room temperature that can be switched by an applied electric field.

Positron Lifetime Studies of Polyaniline Conducting Polymers

1995 ◽  
Vol 413 ◽  
Author(s):  
C. M. Huang ◽  
J. Liu ◽  
T. C. Sandreczki ◽  
Y. C. Jean
Keyword(s):  
Positron Annihilation ◽  
Room Temperature ◽  
Positron Lifetime ◽  
The Other ◽  
Chemical Compositions ◽  
Lifetime Measurements ◽  
Positron Annihilation Lifetime ◽  
Positron Lifetimes ◽  
Lifetime Studies ◽  
Made In

ABSTRACTPositron annihilation lifetime measurements are made in a series of polyaniline polymers with different chemical compositions and protonation ratios at room temperature. Two positron lifetimes are observed in these materials: one is assigned to annihilation in the bulk and the other to voids created due to protonation. A relationship between conductivities and positron annihilation probabilities is found.

Notizen: Positron Annihilation in Noble Gas Mixtures

1979 ◽  
Vol 34 (3) ◽  
pp. 391-393
Author(s):  
P. S. Grover
Keyword(s):  
Electric Field ◽  
Positron Annihilation ◽  
Applied Electric Field ◽  
Decay Constant ◽  
Noble Gas ◽  
Gas Mixtures ◽  
Gas Mixture

Abstract The annihilation decay constant of positrons in (He + Ne + Ar) mixtures has been computed and its dependence on concentration and electric field investigated. This constant is found to depend quite sensitively on the nature of the gas mixture and the applied electric field.

On the Interaction of Positrons with Argon

1972 ◽  
Vol 50 (8) ◽  
pp. 821-825 ◽  
Author(s):  
Peter W. Hewson ◽  
Garth Jones ◽  
Erich W. Vogt
Keyword(s):  
Electric Field ◽  
Positron Annihilation ◽  
Field Dependence ◽  
Local Density ◽  
Polarization Potential ◽  
Annihilation Rate ◽  
Temperature Dependent ◽  
Electric Field Dependence ◽  
Enhancement Factors ◽  
Good Agreement

A semi-phenomenological model of the interaction of positrons with atoms is outlined, and some model properties—enhancement factors, effective mass, and effective charge—are calculated using a local density approximation. These properties are used with a one parameter polarization potential to predict the electric field dependence and the temperature dependence of the positron annihilation rate in argon gas. Comparison of these predictions with experimental data shows good agreement for the electric field dependence, but the predicted temperature dependent effect is less than published experimental results. The model is also applied to helium, with unsatisfactory results, and a prediction of the electric field dependence of the positron annihilation rate in krypton is made.

Nanorods of Dy Modified BiFeO3 for Multifunctional Device Applications

2011 ◽  
Vol 1303 ◽  
Author(s):  
M. Mandal ◽  
S. P. Duttagupta ◽  
V. R. Palkar
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Applied Electric Field ◽  
Room Temperature ◽  
Lateral Displacement ◽  
Ferroelectric Properties ◽  
Magnetic Domain ◽  
Base Material ◽  
Coupling Behavior ◽  
Device Applications

ABSTRACTWe have developed material (Bi0.7Dy0.3FeO3)(BDFO) which exhibits the multiferroic behavior at room temperature with significant coupling in bulk as well as thin films. If these properties could be fashioned in nano rods, implementation in devices could be certainly more prominent and straight forward. We have therefore used vertically aligned arrays of silicon rods (~5 μm in length and ~ 500 nm in diameter) as base material to direct the growth of BDFO in rod form. BDFO is deposited on the surface of Si rods by using pulsed laser deposition technique. These BDFO/Si rods are then separated from the support, dispersed into propanol and transferred onto SiO2/Si substrates for testing. X-ray diffraction (XRD) results indicate presence of phase pure BDFO layer on Si rods. Saturation observed at room temperature in magnetic and ferroelectric hysteresis loops confirm the coexistence of ferromagnetic and ferroelectric properties. Change in ferroelectric polarization measured on single rod in the presence of applied magnetic field suggests the coupling behavior between two order parameters. Moreover, change in magnetic domain pattern of BDFO rods associated with applied electric field further supports the presence of coupling behavior in both ways. The vertical and lateral displacement occurring in BDFO/Si rods with applied electric field helps to confirm their piezoresponce behavior. BDFO/Si nanorods with multifunctional properties could find variety of novel device applications with flexibility and simplicity in operation. It might include single rod power generation by means of applied stress or magnetic field.

Positron Annihilation Rate Variation in the Presence of Electric and Magnetic Fields

1975 ◽  
Vol 53 (2) ◽  
pp. 133-139 ◽  
Author(s):  
M. P. Srivastava ◽  
P. S. Grover
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Electric Field ◽  
Positron Annihilation ◽  
Applied Magnetic Field ◽  
Noble Gases ◽  
Rate Variation ◽  
Annihilation Rate ◽  
Electric And Magnetic Fields ◽  
The Magnetic Field

The variation of the positron annihilation rate λa in noble gases He, Ne, and Ar has been studied in the presence of an external applied magnetic field, when the electric field is kept constant. It is found that λa increases as the magnetic field is increased. In the case of Ar, the dependence is quite appreciable whereas in He and Ne it is comparatively smaller.

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