X-ray Excitation (x-ray + excitation)

Distribution by Scientific Domains


Selected Abstracts


Scintillation from Eu2+ in Nanocrystallized Glass

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2009
Jie Fu
A Eu2+ -doped SiO2,Al2O3,CaO,CaF2 glass was prepared and converted into a transparent glass ceramic by heat treatment. The crystalline phase and its size were determined by X-ray diffraction and a transmission electron microscopy. The scintillation of Eu2+ ions in both glass and ceramic under X-ray excitation was investigated and compared with that in a single-crystal scintillator. [source]


Gemini near-infrared integral field spectroscopy of the narrow-line region of ESO 428,G14: kinematics, excitation and the role of the radio jet

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2006
Rogemar A. Riffel
ABSTRACT We present two-dimensional (2D) gas kinematics and excitation of the inner 300 pc of the Seyfert galaxy ESO 428,G14 at a sampling of 14 pc2, from near-infrared spectroscopic observations at R, 6000 obtained with the Integral Field Unit (IFU) of the Gemini Near-Infrared Spectrograph. From measurements of fluxes and profiles of the emission lines [Fe ii],1.257 ,m, Pa,, H2, 2.121 ,m and Br,, we construct 2D maps of line intensities and ratios, radial velocities and velocity dispersions. Emission line ,tomography' is provided by velocity slices obtained across the line profiles, a unique capability of IFUs, which allows the mapping of not only the peak velocities but including also the wings. We compare these maps with a previously published high spatial resolution radio map and find a tight relation between the radio structure and the emission-line flux distributions and kinematics, revealing that the radio jet plays a fundamental role not only in shaping the narrow-line region but also in the imprint of its kinematics. Blueshifts of up to 400 km s,1 and velocity dispersions of up to 150 km s,1 are observed in association with the radio jet at a position angle (PA) = 129, which is also the PA of the photometric major axis of the galaxy. We conclude that the radio jet is launched at a small angle relative to the galactic plane, with the north-western side slightly oriented towards us. This angle is small enough for the radio jet to shock and compress the gas in the plane of the galaxy, and for the nuclear continuum to ionize and heat it. The distinct kinematics and flux distributions observed for the different emission lines suggest different origins for their emission. The [Fe ii] shows the largest blueshifts and velocity dispersions and its flux distribution is concentrated along the jet, while the H2 shows the lowest velocity dispersions and has additional flux contribution from regions beyond the jet. Both X-rays emitted by the active galactic nucleus and shocks produced by the radio jet can excite the H2 and [Fe ii] emission lines. We use the 2D velocity dispersion maps to estimate upper limits to the contribution of the radio jet to the excitation of [Fe ii] and H2 which may reach 90 per cent for [Fe ii] and 80 per cent for H2 in the jet region. The [Fe ii]/Pa, emission-line ratios and the association of the [Fe ii] flux distribution and kinematics with the radio structure support a stronger contribution of the radio jet to the [Fe ii] excitation than that of H2. In the regions beyond the jet, the observations favour X-ray excitation. [source]


host-defect luminescence of stishovite

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2005
A. Trukhin
Abstract a detailed study of the 4.75 eV luminescence band of stishovite single crystal (SiO2 with rutile structure) is reported. Kinetics of luminescence intensity is studied at durable (tens of minutes) X-ray excitation. The observed behaviour of the band intensity is explained by creation and destruction of luminescence centres depending on temperature both being determined by radiation stimulated diffusion of atomic particles. The luminescence decay is observed to last for minutes after X-ray irradiation while only for ns and hundreds of s under pulsed e-beam irradiation suggesting a complicated recombination of the created defects. The UV band of stishovite is compared with the 4.9 eV luminescence band in ,-quartz, which could not be created by X-ray. the latter being associated with transient centres created by destructive electron-beam irradiation or with permanent centres at neutron or ,-irradiation, and with oxygen-deficient luminescence of silica glass. ( 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Crystal growth, optical and luminescence properties of (Ce,Sr)-doped PrAlO3 single crystals

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2007
A. Novoselov
Abstract Using the micro-pulling-down method, (Ce,Sr)-doped PrAlO3 square-shaped single crystals (4412 mm) were grown. Structural parameters studied by X-ray powder diffraction were consistent with R3m space group. Compositional homogeneity was checked with electron probe micro-analysis and found quite uniform. Absorption spectra and luminescence characteristics under UV and X-ray excitations were measured at room temperature with no Ce-related emission appeared. ( 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Trap-sensitive relaxation of hot carriers in ZnO:Cu,Al

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2006
I. Konovalov
Abstract Modulated photoconductivity measurements with x-ray excitation were performed on ZnO:Cu,Al thin films. We found a strong variation of the modulated photocurrent with temperature starting from the excitation energy approximately equal the binding energy of Cu 2p3 core electrons and above. Strong temperature sensitivity at ,280 K suggests participation of thermally activated trap states in the process of hot carrier relaxation. The shape of the temperature dependence was satisfactorily fitted by the respective calculation. No comparable deviations of the temperature sensitivity were observed when the Cu 2s electrons were excited. We explain the observations by assumption of fast local transitions from a valley in the conduction band into the trap state according to the symmetry selection rules. ( 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]