Photoquenching Of Persistent Photoconductivity In N-Type GaN

1997 ◽  
Vol 482 ◽  
Author(s):  
Michèle T. Hirsch ◽  
O. Seiferta ◽  
O. Kirfel ◽  
J. Parisia ◽  
J. A. Wolk ◽  
...  
Keyword(s):  
Wavelength Range ◽  
Cross Sections ◽  
Spectral Dependence ◽  
Room Temperature ◽  
Preliminary Investigation ◽  
Low Energy ◽  
Persistent Photoconductivity ◽  
Quenching Effect ◽  
Optical Quenching ◽  
Thermally Activated

AbstractWe report on the observation of optical quenching of persistent photoconductivity (PPC) in unintentionally doped n-type GaN films. The PPC is induced by subbandgap illumination between room temperature and 77K. The corresponding decay, which.is thermally activated, is substantially increased upon low energy illumination, e.g. illumination by wavelengths between 1O50nm and 700nm. We measure the saturation conductivity under simultaneous illumination with excitation and quenching light and find that some wavelengths can induce both excitation and quenching of photoconductivity. Additionally, we present a preliminary investigation of the spectral dependence of the quenching effect. A simulation indicates only a weak spectral dependence of the quenching cross-sections in the wavelength range from 470nm–1050nm.

New Features of Dark and Photoconductivity Response of Low Energy Ar+ Ion bombarded GaAs

1989 ◽  
Vol 147 ◽  
Author(s):  
A. Vaseashta ◽  
L. C. Burton
Keyword(s):  
Low Energy ◽  
Persistent Photoconductivity ◽  
Quenching Rate ◽  
Gaas Sample ◽  
Thermally Activated ◽  
Trap Location ◽  
Photoconductivity Response

AbstractPhotoconductivity measurements have been made on three SI GaAs sample types: Ar+ ion etched at leV, 3keV, and unetched. Measurements were made versus time, wavelength, and temperature. Photoquenching was done at 1.19 and 2.0eV energy.Some distinct changes in photoconductive properties are caused by the ion etch: 1) Increase in dark resistance; 2) presence of persistent photoconductivity; 3) increased photosensitivity; 4) increase In quenching rate under 2eV illumination; 5) destruction of the 0.47eV thermally activated photoconductivity.All samples exhibit Shockley-Read recombination controlled photoconductivity below a temperature of 125K, with the same apparent trap location, at 0.26eV above EF.

scholarly journals Electron Transport Coefficients in Hydrogen and Deuterium

1968 ◽  
Vol 21 (1) ◽  
pp. 43 ◽  
Author(s):  
RW Crompton ◽  
MT Elford ◽  
AI McIntosh
Keyword(s):  
Diffusion Coefficient ◽  
Low Temperature ◽  
Cross Sections ◽  
Room Temperature ◽  
Transport Coefficients ◽  
Low Energy ◽  
Published Data ◽  
Low Energy Electrons ◽  
Electron Transport Coefficients

Measurements have been made of the drift velocity W and the ratio of diffusion coefficient to mobility D/μ for low energy electrons in deuterium at 77�K, and of D/μ in hydrogen at 77 and 293�K. Tabulated data are given for D/μ within the range 2 x 10−20 ≤ E/N ≤ 1.2 x 10−16 V cm2 and for W within the range 8 x 10−20 ≤ E/N ≤ 9.5 x 10−17 V cm2. The low temperature results show a considerably reduced scatter when oompared with previously published data and are of an aocuracy comparable with the results of recent measurements made at room temperature. The data obtained complement those of Lowke and of McIntosh thus completing a set from which a more acourate determination of low energy elastic and inelastic cross sections can be made.

Surface ultrastructure of danazol treated rat endometrium: A SEM study

1983 ◽  
Vol 41 ◽  
pp. 556-557
Author(s):  
R.P. Apkarian ◽  
J.S. Sanfilippo
Keyword(s):  
Cross Sections ◽  
Reproductive Tract ◽  
Preliminary Investigation ◽  
Breast Disease ◽  
Distal Segment ◽  
Uterine Horn ◽  
Female Reproductive Tract ◽  
Ultrastructural Changes ◽  
Cycle Phase ◽  
Sprague Dawley

The synthetic androgen danazol, is an isoxazol derivative of ethisterone. It is utilized in the treatment of endometriosis, fibrocystic breast disease, and has a potential use as a contraceptive. A study was designed to evaluate the ultrastructural changes associated with danazol therapy in a rat model. The preliminary investigation of the distal segment of the rat uterine horn was undertaken as part of a larger study intended to elucidate the effects of danazol on the female reproductive tract.Cross-sections (2-3 mm in length) of the distal segment of the uterine horn from sixteen Sprague-Dawley rats were prepared for SEM. Ten rats in estrus served as controls and six danazol treated rats were noted to have alterations of the estrus cycle i.e. a lag in cycle phase or noncycling patterns. Specimens were fixed in 3% glutaraldehyde in 0.05M phosphate buffer containing CaCl2 at pH 7.0-7.4 and chilled to 4°C. After a brief wash in distilled water, specimens were passed through a graded series of ethanol, critical point dryed in CO2 from absolute ethanol, and coated with 6nm Au. Observations were made with an IS1-40 SEM operated at 15kV.

Persistent Photoconductivity And Thermal Recovery Kinetics Of Low Energy Ar + Bombarded GaAs

1991 ◽  
Vol 223 ◽  
Author(s):  
A. Vaseashta ◽  
L. C. Burton
Keyword(s):  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Thermal Recovery ◽  
Low Energy ◽  
Persistent Photoconductivity ◽  
Transport Parameters ◽  
Excellent Correlation ◽  
Proposed Model ◽  
Transient Spectroscopy ◽  
Kinetics Of

ABSTRACTKinetics of persistent photoconductivity, photoquenching, and thermal and optical recovery observed in low energy Ar+ bombarded on (100) GaAs surfaces have been investigated. Rate and transport equations for these processes were derived and simulated employing transport parameters, trap locations and densities determined by deep level transient spectroscopy. Excellent correlation was obtained between the results of preliminary simulation and the experimentally observed values. The exponential decay of persistent photoconductivity response curve was determined to be due to metastable electron traps with longer lifetime and is consistent with an earlier proposed model.

Mass spectrometric study of allyl radical, allyl bromide and 1,5-hexadiene interactions with oxides; Cobalt suboxide Co3O4

1979 ◽  
Vol 44 (7) ◽  
pp. 2009-2014 ◽  
Author(s):  
Jana Nováková ◽  
Zdeněk Dolejšek
Keyword(s):  
Room Temperature ◽  
Allyl Bromide ◽  
Catalytic Properties ◽  
Mass Spectrometric Study ◽  
Spectrometric Study ◽  
Flow Conditions ◽  
Allyl Radical ◽  
Knudsen Flow ◽  
Thermally Activated ◽  
Radical Interaction

Products of (a) allyl radical interaction with unheated Co3O4, (b) thermally activated 1,5-hexadiene or thermally activated allyl bromide with unheated Co3O4, (c) moderately heated Co3O4 with unheated 1,5-hexadiene or allyl bromide were studied under Knudsen flow conditions. Cobalt suboxide Co3O4, a typical catalyst of deep oxidations yielded acrolein in reaction with allyl radicals as early as at the room temperature of the catalyst. A similar acrolein formation was also observed in the allyl radical interaction with other oxides exhibiting different catalytic properties. It appears that acrolein is in general the primary product of the allyl radical interaction with the oxides. The results are discussed and compared with previous data obtained with MoO3.

scholarly journals Charmed and bottomed hadronic cross sections from a statistical model

2020 ◽  
Vol 56 (9) ◽  
Author(s):  
Gábor Balassa ◽  
György Wolf
Keyword(s):  
Statistical Model ◽  
Energy Range ◽  
Cross Sections ◽  
Heavy Quarks ◽  
Open Charm ◽  
Low Energy ◽  
Final State ◽  
Proton Antiproton ◽  
Proton Proton

Abstract In this work, we extended our statistical model with charmed and bottomed hadrons, and fit the quark creational probabilities for the heavy quarks, using low energy inclusive charmonium and bottomonium data. With the finalized fit for all the relevant types of quarks (up, down, strange, charm, bottom) at the energy range from a few GeV up to a few tens of GeV’s, the model is now considered complete. Some examples are also given for proton–proton, pion–proton, and proton–antiproton collisions with charmonium, bottomonium, and open charm hadrons in the final state.

scholarly journals Low Energy Antikaon-nucleon/nuclei interaction studies by AMADEUS

2019 ◽  
Vol 199 ◽  
pp. 01014
Author(s):  
K. Piscicchia ◽  
M. Bazzi ◽  
G. Belloti ◽  
A. M. Bragadireanu ◽  
D. Bosnar ◽  
...  
Keyword(s):  
Cross Sections ◽  
Transition Amplitude ◽  
Nuclear Interaction ◽  
Branching Ratios ◽  
Analysis Procedure ◽  
Low Energy ◽  
Carbon Target ◽  
Pure Carbon ◽  
Nuclear Targets ◽  
Mass Spectroscopic Study

The AMADEUS experiment at the DAΦNE collider of LNF-INFN deals with the investigation of the at-rest, or low-momentum, K− interactions in light nuclear targets, with the aim to constrain the low energy QCD models in the strangeness sector. The 0 step of the experiment consisted in the reanalysis of the 2004/2005 KLOE data, exploiting K− absorptions in H, 4He, 9Be and 12C, leading to the first invariant mass spectroscopic study with very low momentum (about 100 MeV) in-flight K− captures. With AMADEUS step 1 a dedicated pure Carbon target was implemented in the central region of the KLOE detector, providing a high statistic sample of pure at-rest K− nuclear interaction. The first measurement of the non-resonant transition amplitude $\left| {{A_{{K^ - }n \to \Lambda {\pi ^ - }}}} \right|$ at $\sqrt s = 33\,MeV$ below the K̄N threshold is presented, in relation with the Λ(1405) properties studies. The analysis procedure adopted in the serarch for K− multi-nucleon absorption cross sections and Branching Ratios will be also described.

scholarly journals LEvEL: Low-Energy Neutrino Experiment at the LHC

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Kevin J. Kelly ◽  
Pedro A. N. Machado ◽  
Alberto Marchionni ◽  
Yuber F. Perez-Gonzalez
Keyword(s):  
Cross Sections ◽  
Hadron Collider ◽  
Neutrino Flux ◽  
Coherent Scattering ◽  
Forward Direction ◽  
Low Energy ◽  
Neutrino Experiment ◽  
Beam Dump ◽  
Neutrino Production ◽  
Energy Neutrino

Abstract We propose the operation of LEvEL, the Low-Energy Neutrino Experiment at the LHC, a neutrino detector near the Large Hadron Collider Beam Dump. Such a detector is capable of exploring an intense, low-energy neutrino flux and can measure neutrino cross sections that have previously never been observed. These cross sections can inform other future neutrino experiments, such as those aiming to observe neutrinos from supernovae, allowing such measurements to accomplish their fundamental physics goals. We perform detailed simulations to determine neutrino production at the LHC beam dump, as well as neutron and muon backgrounds. Measurements at a few to ten percent precision of neutrino-argon charged current and neutrino-nucleus coherent scattering cross sections are attainable with 100 ton-year and 1 ton-year exposures at LEvEL, respectively, concurrent with the operation of the High Luminosity LHC. We also estimate signal and backgrounds for an experiment exploiting the forward direction of the LHC beam dump, which could measure neutrinos above 100 GeV.

scholarly journals Temperature-Dependent Stimulated Emission Cross-Section in Nd3+:YLF Crystal

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 431
Author(s):  
Giorgio Turri ◽  
Scott Webster ◽  
Michael Bass ◽  
Alessandra Toncelli
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Room Temperature ◽  
Radiative Decay ◽  
Emission Cross Section ◽  
Spectroscopic Properties ◽  
Stimulated Emission ◽  
Different Temperatures ◽  
Stimulated Emission Cross Section ◽  
Semi Empirical

Spectroscopic properties of neodymium-doped yttrium lithium fluoride were measured at different temperatures from 35 K to 350 K in specimens with 1 at% Nd3+ concentration. The absorption spectrum was measured at room temperature from 400 to 900 nm. The decay dynamics of the 4F3/2 multiplet was investigated by measuring the fluorescence lifetime as a function of the sample temperature, and the radiative decay time was derived by extrapolation to 0 K. The stimulated-emission cross-sections of the transitions from the 4F3/2 to the 4I9/2, 4I11/2, and 4I13/2 levels were obtained from the fluorescence spectrum measured at different temperatures, using the Aull–Jenssen technique. The results show consistency with most results previously published at room temperature, extending them over a broader range of temperatures. A semi-empirical formula for the magnitude of the stimulated-emission cross-section as a function of temperature in the 250 K to 350 K temperature range, is presented for the most intense transitions to the 4I11/2 and 4I13/2 levels.

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