scholarly journals Hydrogen induced trap states in TiO2 probed by resonant X-ray photoemission

2021 ◽  
Author(s):  
Emanuel Billeter ◽  
Andrea Sterzi ◽  
Abdessalem Aribia ◽  
Cesare Graziolie ◽  
Marcello Coreno ◽  
...  
Keyword(s):  
Trap States ◽  
X Ray

scholarly journals Growth and Characterisation of Layered (BA)2CsAgBiBr7 Double Perovskite Single Crystals for Application in Radiation Sensing

Crystals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1208
Author(s):  
Valeria Murgulov ◽  
Catherine Schweinle ◽  
Michael Daub ◽  
Harald Hillebrecht ◽  
Michael Fiederle ◽  
...  
Keyword(s):  
Single Crystals ◽  
Double Perovskite ◽  
Monoclinic Space Group ◽  
Trap States ◽  
Structure Property ◽  
X Ray ◽  
Structure Property Relationship ◽  
Lattice Planes ◽  
Radiation Sensors ◽  
Lower Resistivity

A recent publication on single crystals of two-dimensional, layered organic–inorganic (BA)2CsAgBiBr7 double perovskite (BA+ = ) suggested the great potential of this semiconductor material in the detection of X-ray radiation. Our powder XRD measurement confirms the crystallinity and purity of all samples that crystallise in the monoclinic space group , while the single crystal XRD measurements reveal the dominant {001} lattice planes. The structure–property relationship is reflected in the lower resistivity values determined from the van der Pauw measurements (1.65–9.16 × 1010 Ωcm) compared to those determined from the IV measurements (4.19 × 1011–2.67 × 1012 Ωcm). The density of trap states and charge-carrier mobilities, which are determined from the IV measurements, are 1.12–1.76 × 1011 cm–3 and 10−5–10−4 cm2V–1s–1, respectively. The X-ray photoresponse measurements indicate that the (BA)2CsAgBiBr7 samples synthesised in this study satisfy the requirements for radiation sensors. Further advances in crystal growth are required to reduce the density of defects and improve the performance of single crystals.

Characterization of Highly Luminescent LaPO4:Eu3+/LaPO4 One-Dimensional Core/Shell Heterostructures

2008 ◽  
Vol 8 (3) ◽  
pp. 1266-1271 ◽  
Author(s):  
Wenbo Bu ◽  
Jianlin Shi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Core Shell ◽  
Trap States ◽  
Hydrothermal Conditions ◽  
One Dimensional ◽  
X Ray ◽  
Luminescence Efficiency ◽  
Transmission Electron

Highly luminescent LaPO4:Eu3+/LaPO4 one-dimensional (1D) core/shell heterostructures were successfully synthesized by a mild and simple self-aggregation process under refluxing or hydrothermal conditions. The resulting 1D core/shell heterostructures were characterized using a variety of techniques including X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and X-ray photoelectron spectroscopy (XPS) to demonstrate successful coating by the crystalline LaPO4. In addition, a possible formation mechanism for this core/shell heterostructure was proposed. Finally, the photoluminescence property of the LaPO4:Eu3+/LaPO4 1D core/shell heterostructures was investigated in detail, which illustrates that the core/shell heterostructures remarkably increase the luminescence efficiency because the LaPO4 shells effectively eliminate surface trap-states and suppress the energy quenching in the energy-transfer processes.

One-pot room temperature synthesizing Cu- and Mn-doped ZnSe nanocrystals by a rapid photochemical method

2016 ◽  
Vol 30 (11) ◽  
pp. 1650227 ◽  
Author(s):  
A. R. Bahador ◽  
M. Molaei ◽  
M. Karimipour
Keyword(s):  
Room Temperature ◽  
Photochemical Synthesis ◽  
Trap States ◽  
One Pot ◽  
X Ray ◽  
Excitonic Emission ◽  
Ft Ir ◽  
Pl Intensity ◽  
Mn Doped ◽  
Znse Nanocrystals

In this work, a one-pot, rapid, green and room temperature photochemical synthesis of transition metal (TM; Cu, Mn)-doped ZnSe nanocrystals (NCs) was reported. NCs were successfully characterized using Fourier transform-infrared (FT-IR), photoluminescence (PL) and UV-Visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), X-ray diffractometry (XRD) and energy dispersive X-ray spectra (EDX). FT-IR spectra confirmed the capping of ZnSe by thioglycolic acid (TGA) molecules. XRD and TEM analysis demonstrated zinc blend phase NCs with an average size of around 3 nm. Band gap of ZnSe NCs was about 3.6 eV which it was decreased by increasing the illumination time. PL spectra of ZnSe NCs showed a broad emission with two peaks located at 380 nm and 490 nm related to excitonic and trap states emission, respectively. For ZnSe:Cu NCs, excitonic emission disappeared completely and PL intensity of trap states emission increased with the increase in the Cu[Formula: see text] ion concentration so that for precursor ratio of Cu:Zn 1%, optimal value of PL intensity was obtained. For ZnSe:Mn NCs, the excitonic emission decreased gradually with the increase in the impurity concentration whereas trap state emission increased. Moreover, a peak about 590 nm was appeared from 4T1-6A1 transition of the Mn[Formula: see text] impurity, demonstrating the Mn incorporation inside the ZnSe NCs structure.

Surface Photovoltage Spectroscopy for the Investigation of Perovskite Oxide Interfaces

2005 ◽  
Vol 902 ◽  
Author(s):  
Elke Beyreuther ◽  
Stefan Grafström ◽  
Christian Thiele ◽  
Kathrin Dörr ◽  
Lukas M. Eng
Keyword(s):  
Photoelectron Spectroscopy ◽  
Perovskite Oxide ◽  
Surface Photovoltage ◽  
Epitaxial Thin Films ◽  
Trap States ◽  
Oxide Interfaces ◽  
X Ray ◽  
Surface Photovoltage Spectroscopy ◽  
Prepared State ◽  
Capacitive Method

AbstractIn the present study, we comparatively investigate the distribution of electronic interface states of three different perovskite oxide interfaces, formed by epitaxial thin films of La0.7Sr0.3MnO3 (LSMO), La0.7Ca0.3MnO3 (LCMO), and La0.7Ce0.3MnO3 (LCeMO) on SrTiO3(100) substrates, in the as-prepared state as well as after an annealing procedure. We find that annealing significantly reduces the number and density of interface trap states. Two different experimental realizations of the surface photovoltage spectroscopy (SPS) technique were employed: an approach based on X-ray photoelectron spectroscopy (XPS), as well as a capacitive method. The advantages and limitations of both methods are critically discussed.

Fluoreszenz-Spektroskopie an dünnen im UHV aufgedampften Coronen-Schichten

1992 ◽  
Vol 47 (5) ◽  
pp. 643-659
Author(s):  
H. Port ◽  
H.C. Wolf
Keyword(s):  
Thin Films ◽  
Fluorescence Spectra ◽  
Structural Modification ◽  
Trap States ◽  
Excitation Spectra ◽  
Fluorescence Excitation ◽  
X Ray ◽  
Fluorescence Excitation Spectra ◽  
Inorganic Substrates ◽  
Crystal Type

Abstract Fluorescence Spectroscopy on UHV-Deposited Thin Films of CoroneneThin films of coronene, UHV-deposited on different inorganic substrates (Si(111), Si(100), Si/Si02, graphite(0001) and MoS2(0001)) have been investigated via laser induced fluorescence and fluorescence excitation spectra at various coronene coverages (from submonolayers to 1000 Å) and temperatures (4.2 K - 300 K). Independent of the substrate the films reveal a characteristic absorption which is red-shifted with respect to that of the coronene crystal and is attributed to a new film-specific structural modification (in accord with X-ray data). At film thicknesses d > 50 Å this absorption is increasingly superimposed by crystal-type absorption. The fluorescence spectra at low coverages and low temperatures strongly depend on the substrate. On Si/Si02, graphite and MoS2 the fluorescence is similar to that of the coronene crystal. Thin films on Si(100) and Si(111), on the other hand, show monomer-like narrowband fluorescence originating, presumably, in substrate-induced trap states

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

Some Problems in Understanding the Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 1-9
Author(s):  
A. H. Gabriel
Keyword(s):  
Solar Corona ◽  
Solar Atmosphere ◽  
Theoretical Modelling ◽  
Total System ◽  
Major Advance ◽  
X Ray ◽  
Proper Perspective ◽  
Space Observations

The development of the physics of the solar atmosphere during the last 50 years has been greatly influenced by the increasing capability of observations made from space. Access to images and spectra of the hotter plasma in the UV, XUV and X-ray regions provided a major advance over the few coronal forbidden lines seen in the visible and enabled the cooler chromospheric and photospheric plasma to be seen in its proper perspective, as part of a total system. In this way space observations have stimulated new and important advances, not only in space but also in ground-based observations and theoretical modelling, so that today we find a well-balanced harmony between the three techniques.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

Iron K-Line Emission from X-Ray Binaries

1988 ◽  
Vol 102 ◽  
pp. 47-50
Author(s):  
K. Masai ◽  
S. Hayakawa ◽  
F. Nagase
Keyword(s):  
Accretion Disk ◽  
Radiative Recombination ◽  
Characteristic Temperature ◽  
Line Emission ◽  
Ionization Front ◽  
Continuum Radiation ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

AbstractEmission mechanisms of the iron Kα-lines in X-ray binaries are discussed in relation with the characteristic temperature Txof continuum radiation thereof. The 6.7 keV line is ascribed to radiative recombination followed by cascades in a corona of ∼ 100 eV formed above the accretion disk. This mechanism is attained for Tx≲ 10 keV as observed for low mass X-ray binaries. The 6.4 keV line observed for binary X-ray pulsars with Tx> 10 keV is likely due to fluorescence outside the He II ionization front.

Diagnostics of Gold Laser Plasmas

1988 ◽  
Vol 102 ◽  
pp. 357-360
Author(s):  
J.C. Gauthier ◽  
J.P. Geindre ◽  
P. Monier ◽  
C. Chenais-Popovics ◽  
N. Tragin ◽  
...  
Keyword(s):  
Experimental Results ◽  
Pure Gold ◽  
Electronic Temperature ◽  
X Ray ◽  
Laser Plasmas ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractIn order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-Z plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma.

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