Observation of dynamically induced fluctuations of the photon flux and resolution of the broad luminescence band of Cs2TeBr6

1985 ◽  
Vol 67 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Joachim Degen ◽  
Hans -Herbert Schmidtke ◽  
C. A. Chatzidimitriou-Dreismann
Keyword(s):  
Luminescence Band ◽  
Photon Flux ◽  
Broad Luminescence Band

OPTICAL PROPERTIES OF ANATASE TiO2 UNDER THE HIGH PRESSURE

2001 ◽  
Vol 15 (28n30) ◽  
pp. 3952-3955 ◽  
Author(s):  
TAKAO SEKIYA ◽  
SHINSUKE OHTA ◽  
SUSUMU KURITA
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Optical Properties ◽  
Lower Energy ◽  
Luminescence Band ◽  
High Pressures ◽  
Anatase Tio2 ◽  
Broad Luminescence Band ◽  
Pressure Phase ◽  
Energy Side

Optical absorption, luminescence and Raman spectra were measured for anatase TiO 2 under high pressures. The pressure dependence of Raman frequencies is determined. The absorption edge of anatase shifts to higher energy side with increasing pressure and the edge jumps abruptly to lower energy side on the phase transition. A broad luminescence band of anatase shifts also to higher energy side with increasing pressure. These experimental results reveal that the pressure-induced phase transition from anatase to high-pressure phase arises in the range of 4.0-4.6 GPa.

scholarly journals Effect of impurities and disordering on the photoluminescence of crystals and glasses in the system Li2O - 7GeO2

2019 ◽  
Vol 27 (1) ◽  
pp. 51-56
Author(s):  
O. V. Ohiienko ◽  
V. N. Moiseienko ◽  
M. D. Volnyanskij
Keyword(s):  
Luminescence Band ◽  
Material Structure ◽  
Excitation Wavelength ◽  
Photoluminescence Spectra ◽  
Broad Luminescence Band ◽  
Intense Luminescence ◽  
Doped Glasses ◽  
Effect Of Impurities ◽  
Oxygen Complexes ◽  
Octahedral Configuration

The work is devoted to the study of photoluminescence spectra of weakly polar ferroelectric crystals Li2Ge7O15 and Li2O – 7GeO2 glasses. For all initial samples was observed the wide intensive luminescence band with maximum in the region of 525–550 nm. The spectral distribution of intensity and the position of the maximum of the band for a Li2Ge7O15 crystal depended on the excitation wavelength (λex=405 nm or 365nm were used). The spectral profile of the luminescence band was broadened in glass containing of 0.67% copper. The intensity of the luminescence band was decreased 6 times for glass doped with Cr3+ ions (0.01%) as compared with glass containing Cu2+ ions. The intense luminescence band of Cr3+ ions with λmax=659nm was appeared starting from 600. The assumption about the nature of the broad luminescence band observed in both nominally pure and doped glasses and crystals was made: the source of luminescence can be germanium - oxygen complexes [GeO4] and [GeO6] of the tetrahedral and octahedral configuration in the material structure.

CRYSTAL STRUCTURE AND LUMINESCENT PROPERTIES OF Sr2B2O5:Eu2+ BLUE PHOSPHORS

2013 ◽  
Vol 06 (03) ◽  
pp. 1350034 ◽  
Author(s):  
QUAN-SHENG LIU ◽  
ZHAO-YANG ZHENG ◽  
LI-QUN CHENG ◽  
XI-YAN ZHANG ◽  
YUE SONG ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Energy Level ◽  
Ground State ◽  
Luminescence Band ◽  
Energy State ◽  
Luminescent Properties ◽  
Low Energy ◽  
Monoclinic System ◽  
Broad Luminescence Band ◽  
Ion Doping

The Sr2B2O5:Eu2+ phosphor was synthesized by high-temperature solid state reaction. The crystal structure of Sr2B2O5:Eu2+ phosphor is monoclinic system with space group of P21/a(14). Due to Eu2+ ion doping, the lattice parameters and unit cell volume decreased. The luminescence spectrum is a broad luminescence band peaking at 468 nm and 478 nm, which corresponds to the transition of 5d-low energy state in Eu2 and Eu1 to the ground state. The excitation spectrum is at UV region less than 264 nm corresponding to the band gap transition of borate host. The low energy level of 5d-band locates 20921 cm-1, the band width is 1 eV. The electronegativity of O2- anions around Eu1 and Eu2 is 3.147 eV and 3.326 eV respectively, which determines the split of 5d energy level.

Crystal Structure and Optical Properties of 4-[4-(Dimethylamino)- styryl]-1-methyl-pyridinium Lead Tribromide

2003 ◽  
Vol 58 (8) ◽  
pp. 815-816 ◽  
Author(s):  
George C. Papavassiliou ◽  
George A. Mousdis ◽  
Aris Terzis ◽  
Caterina P. Raptopoulou
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Laser Radiation ◽  
Title Compound ◽  
Luminescence Band ◽  
Space Group ◽  
Broad Luminescence Band ◽  
Centrosymmetric Space Group

The title compound crystallizes in the centrosymmetric space group I2/a. When pumped by 458 and 1064 nm laser radiation the compound gives rise to a broad luminescence band at ca. 668 and 671 nm, respectively.

TIME-RESOLVED PHOTOLUMINESCENCE OF EXCITONS IN HgI2

2001 ◽  
Vol 15 (28n30) ◽  
pp. 3920-3923 ◽  
Author(s):  
N. OHNO ◽  
X. M. WEN
Keyword(s):  
Radiative Recombination ◽  
Luminescence Band ◽  
Broad Band ◽  
Relaxation Processes ◽  
Time Resolved ◽  
Carrier Lifetimes ◽  
Broad Luminescence Band ◽  
Donor Acceptor ◽  
Exciton Annihilation ◽  
Time Resolved Photoluminescence

The time-resolved photoluminescence (TRPL) of red HgI 2 single crystal has been measured to determine the carrier lifetimes and to reveal the energy relaxation of excitons. Sharp near-bandgap luminescence lines due to free and bound excitons are observed at 530 nm, and a broad luminescence band appears at 630 nm at low temperatures. TRPL experiments of the near-bandgap luminescence have revealed that the luminescence comprise fast (30 to 200 ps) and slow (100 to 400 ps) decay components, showing several relaxation processes in free and bound exciton annihilation. TRPL of the broad band at 630 nm has shown that the luminescence is ascribed to the radiative recombination of donor-acceptor (DA) pairs.

Low Temperature Photoluminescence and Photoinduced Current Spectroscopy on CdZnTe Grown by High-Pressure Bridgman Technique

1999 ◽  
Vol 588 ◽  
Author(s):  
A. Zerrai ◽  
K. Cherkaoui ◽  
S. Mergui ◽  
A. Zumbiehl ◽  
M. Hage-Ali ◽  
...  
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Luminescence Band ◽  
Thermoelectric Effect ◽  
Bridgman Technique ◽  
Edge Luminescence ◽  
Broad Luminescence Band ◽  
Resistivity Model ◽  
Low Temperature Photoluminescence

AbstractLow temperature photoluminescence (PL), photoinduced current spectroscopy (PICTS) and thermoelectric effect spectroscopy (TEES) measurements have been carried out on several CdZnTe samples, taken from the same ingot, grown by the High Pressure Bridgman Technique. The PL bandgap edge luminescence allowed us to study the quality of the CdZnTe material. We have also determined the zinc segregation through the ingot. A broad luminescence band at lower energies was observed and correlated with PICTS results. The behavior of the defects through the ingot was studied by PICTS. Finally, these results are used to implement the resistivity model.

A photoelectron microscope study of surfaces

1989 ◽  
Vol 47 ◽  
pp. 10-11
Author(s):  
W. Engel ◽  
M. Kordesch ◽  
A. M. Bradshaw ◽  
E. Zeitler
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Field Strength ◽  
Uv Light ◽  
Physical Property ◽  
Photon Flux ◽  
Mercury Lamp ◽  
Object Surface ◽  
The Sixties ◽  
Physical Features

Photoelectron microscopy is as old as electron microscopy itself. Electrons liberated from the object surface by photons are utilized to form an image that is a map of the object's emissivity. This physical property is a function of many parameters, some depending on the physical features of the objects and others on the conditions of the instrument rendering the image.The electron-optical situation is tricky, since the lateral resolution increases with the electric field strength at the object's surface. This, in turn, leads to small distances between the electrodes, restricting the photon flux that should be high for the sake of resolution.The electron-optical development came to fruition in the sixties. Figure 1a shows a typical photoelectron image of a polycrystalline tantalum sample irradiated by the UV light of a high-pressure mercury lamp.

STUDIES OF PHOTONUCLEAR REACTIONS AND PHOTON ACTIVATION ANALYSIS IN THE GIANT DIPOLE RESONANCE REGION USING MICROTRONS

2007 ◽  
Vol 14 (1) ◽  
pp. 42 ◽  
Author(s):  
TRAN DUC THIEP ◽  
NGUYEN VAN DO ◽  
NGUYEN KHAC THI ◽  
TRUONG THI AN ◽  
NGUYEN NGOC SON
Keyword(s):  
Activation Analysis ◽  
Giant Dipole Resonance ◽  
Resonance Region ◽  
Photon Activation Analysis ◽  
Photon Flux ◽  
Photon Activation ◽  
Applied Physics ◽  
Dipole Resonance ◽  
Giant Dipole Resonance Region ◽  
Fission Neutrons

Mictrorons are accelerators of electrons and are simultaneous sources of bremsstrahlung photon flux and fission neutrons. In 1982, a microtron of seventeen trajectories Microtron MT - 17 was put into operation at the National Institute of Physics of Vietnam. Though very modest, microtons are very useful for developing countries such as Vietnam in both fundamental and applied physics research. During the recent years by using the above mentioned MT - 17 and microtrons from other institutes we have carried out different investigations. In this report we present some results obtained in the studies of photonuclear reactions and photon activation analysis in the giant dipole resonance region.

Neutron dose evaluation of Elekta Linac at two energies (10 & 18 MV) by MCNP code and comparison with experimental measurements

2014 ◽  
Vol 6 (1) ◽  
pp. 1006-1015
Author(s):  
Negin Shagholi ◽  
Hassan Ali ◽  
Mahdi Sadeghi ◽  
Arjang Shahvar ◽  
Hoda Darestani ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Measurement Data ◽  
Calculated Data ◽  
High Energy ◽  
Neutron Dose ◽  
Dose Assessment ◽  
Photon Flux ◽  
Dose Equivalent ◽  
Monte Carlo Techniques ◽  
Neutron Dose Equivalent

Medical linear accelerators, besides the clinically high energy electron and photon beams, produce other secondary particles such as neutrons which escalate the delivered dose. In this study the neutron dose at 10 and 18MV Elekta linac was obtained by using TLD600 and TLD700 as well as Monte Carlo simulation. For neutron dose assessment in 2020 cm2 field, TLDs were calibrated at first. Gamma calibration was performed with 10 and 18 MV linac and neutron calibration was done with 241Am-Be neutron source. For simulation, MCNPX code was used then calculated neutron dose equivalent was compared with measurement data. Neutron dose equivalent at 18 MV was measured by using TLDs on the phantom surface and depths of 1, 2, 3.3, 4, 5 and 6 cm. Neutron dose at depths of less than 3.3cm was zero and maximized at the depth of 4 cm (44.39 mSvGy-1), whereas calculation resulted  in the maximum of 2.32 mSvGy-1 at the same depth. Neutron dose at 10 MV was measured by using TLDs on the phantom surface and depths of 1, 2, 2.5, 3.3, 4 and 5 cm. No photoneutron dose was observed at depths of less than 3.3cm and the maximum was at 4cm equal to 5.44mSvGy-1, however, the calculated data showed the maximum of 0.077mSvGy-1 at the same depth. The comparison between measured photo neutron dose and calculated data along the beam axis in different depths, shows that the measurement data were much more than the calculated data, so it seems that TLD600 and TLD700 pairs are not suitable dosimeters for neutron dosimetry in linac central axis due to high photon flux, whereas MCNPX Monte Carlo techniques still remain a valuable tool for photonuclear dose studies.

Quantitative Ratiometric pH Imaging Using a 1,2-Dioxetane Chemiluminescence Resonance Energy Transfer Sensor

2020 ◽  
Author(s):  
Lucas S. Ryan ◽  
Jeni Gerberich ◽  
Uroob Haris ◽  
ralph mason ◽  
Alexander Lippert
Keyword(s):  
Energy Transfer ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Whole Body ◽  
Photon Flux ◽  
Ph Homeostasis ◽  
Ph Imaging ◽  
Confounding Variables ◽  
Significant Difference

<p>Regulation of physiological pH is integral for proper whole-body and cellular function, and disruptions in pH homeostasis can be both a cause and effect of disease. In light of this, many methods have been developed to monitor pH in cells and animals. In this study, we report a chemiluminescence resonance energy transfer (CRET) probe Ratio-pHCL-1, comprised of an acrylamide 1,2-dioxetane chemiluminescent scaffold with an appended pH-sensitive carbofluorescein fluorophore. The probe provides an accurate measurement of pH between 6.8-8.4, making it viable tool for measuring pH in biological systems. Further, its ratiometric output is independent of confounding variables. Quantification of pH can be accomplished both using common fluorimetry and advanced optical imaging methods. Using an IVIS Spectrum, pH can be quantified through tissue with Ratio-pHCL-1, which has been shown in vitro and precisely calibrated in sacrificed mouse models. Initial studies showed that intraperitoneal injections of Ratio-pHCL-1 into sacrificed mice produce a photon flux of more than 10^10 photons per second, and showed a significant difference in ratio of emission intensities between pH 6.0, 7.0, and 8.0.</p> <b></b><i></i><u></u><sub></sub><sup></sup><br>

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