This work is devoted to the development of two novel types of advanced composite scintillators based on single crystalline films (SCFs) of Lu
3
Al
5
O
12
garnet (LuAG), doped with Ce
3+
and Pr
3+
...ions, and substrates from single crystals (SCs) of Sc
3+
doped LuAG using the liquid phase epitaxy (LPE) method. We show the possibility for simultaneous registration of α-particles and γ-quanta using separation of the decay kinetics of the SCF and crystal parts of such composite scintillators. Namely, large differences in the respective scintillation decay kinetics and decay time values
t
α
and
t
γ
are observed for LuAG:Ce SCF/LuAG:Sc SC and LuAG:Pr SCF/LuAG:Sc SC composite scintillators under excitation by α-particles from an
241
Am (5.5 MeV) source and γ-quanta from a
137
Cs (662 keV) source. Thus, both developed types of composite scintillators can be applied for simultaneous registration of α-particles and γ-quanta in mixed radiation fluxes. The rate of discrimination of the scintillation signals, coming from the SCF and SC parts of the LuAG:Ce SCF/LuAG:Sc SC composite scintillator, expressed by the
t
γ
/
t
α
ratio, is equal to 1.34-1.96 in the 0-1100 ns time interval. For the LuAG:Pr SCF/LuAG:Sc SC composite scintillators, more significant differences in the scintillation decay kinetics are achieved. In this case, the
t
γ
/
t
α
ratio for these composite scintillators reaches the values 9.6-15.6 in the wide 0-2500 ns time interval. This is the best result among all the types of composite scintillators we developed based on epitaxial structures of garnet compounds.
Top - Scheme of the composite scintillator for registration of α-particles and γ-quanta. Bottom - Samples of the LuAG:Ce SCF/LuAG:Sc SC (a) and LuAG:Pr SCF/LuAG:Sc SC (b) composite scintillators prepared using the liquid phase epitaxy growth method.
► Comparison of the luminescence and scintillation properties of YAG:Ce crystals, films and transparent ceramic. ► Antisite defects and oxygen vacancies as emission centers in YAG host. ► Influence ...of the boundaries of grains on luminescent properties of YAG:Ce ceramic.
In this work, we have performed the comparative analysis of the luminescent and scintillation properties of Y3Al5O12:Ce (YAG:Ce) single crystals (SC), single crystalline films (SCF) and transparent optical ceramics (OС) using the traditional spectral methods as well as the luminescence spectroscopy under excitation by pulsed synchrotron radiation in the fundamental absorption range of YAG host. We have shown that the properties of YAG:Ce OC are rather closer to the properties of SCF counterpart where YAl antisite defects are completely absent than to the properties of SC of this garnet with large concentration of YAl antisite defects. At the same time, the luminescence spectra of YAG:Ce OC and SC show the emission bands in the 200–450nm range related to YAl antisite defects and charged oxygen vacancies (F+ and F-centers). YAG:Ce ОС also possesses significantly higher thermoluminescence in the range above room temperature and large contribution of slow components in the Ce3+ luminescence decay under high-energy excitation in comparison with SC and SCF of this garnet. The mentioned properties of YAG:Ce OC are caused by the participation of antisite defects and charged oxygen vacancies located in OC mainly on the boundaries of grains, as trapping centers in the energy transfer processes from the host to the Ce3+ ions.
Our work is related to the liquid phase epitaxy-based development of new scintillating screens for high-resolution X-ray imaging. We successfully grew undoped and Tb, Eu and Ce-doped GdAlO
3
as well ...as Gd
x
Lu
1−
x
AlO
3
single crystalline films on YAlO
3
substrates. We studied crystallization conditions as a function of melt composition, growth temperature and lattice mismatch between the film and the substrate. The film composition was measured by using an electron microprobe and the morphology of the film surface was studied by scanning electron microscopy. X-Ray diffraction was used to characterize the crystal structure and the mismatch between the film and the substrate. In addition, the light yield of the Eu
3+
-doped films, as well as the obtained spatial resolution show that Gd
x
Lu
1−
x
AlO
3
may advantageously compete with existing thin film scintillators in particular energy ranges.
High quality and dense GdLuAP:Eu scintillating screens have been successfully grown using liquid phase epitaxy showing superior imaging performances as compared the currently used GGG films.
Scintillator-based X-ray imaging is a powerful technique for noninvasive real-space microscopic structural investigation such as synchrotron-based computed tomography. The resolution of an optical ...image formed by scintillation emission is fundamentally diffraction limited. To overcome this limit, stimulated scintillation emission depletion (SSED) X-ray imaging, based on stimulated emission depletion (STED) microscopy, has been recently developed. This technique imposes new requirements on the scintillator material: efficient de-excitation by the STED-laser and negligible STED-laser excited luminescence. In this work, luminescence depletion was measured in several commonly-used Ce
, Tb
, and Eu
- doped scintillators using various STED lasers. The depletion of Tb
and Eu
via 4f-4f transitions was more efficient (P
= 8…19 mW) than Ce
depletion via 5d-4f transitions (P
= 43…45 mW). Main origins of STED-laser excited luminescence were one- and two-photon excitation, and scintillator impurities. LSO:Tb scintillator and a 628 nm cw STED-laser is the most promising combination for SSED satisfying the above-mentioned requirements.
Absorption, cathodoluminescence, excitation spectra of photoluminescence (PL) and PL decay kinetics were studied at 300K for the double doped with Bi3+–Pr3+ and separately doped with Bi3+ and Pr3+ ...Lu3Al5O12 (LuAG) and Y3Al5O12 (YAG) single crystalline film (SCF) phosphors grown by the liquid phase epitaxy method. The emission bands in the UV range arising from the intrinsic radiative transitions of Bi3+ based centers, and emission bands in the visible range, related to the luminescence of excitons localized around Bi3+ based centers, were identified both in Bi–Pr and Bi-doped LuAG and YAG SCFs. The energy transfer processes from the host lattice simultaneously to Bi3+ and Pr3+ ions and from Bi3+ to Pr3+ ions were investigated. Competition between Pr3+ and Bi3+ ions in the energy transfer processes from the LuAG and YAG hosts was evidenced. The strong decrease of the intensity of Pr3+ luminescence both in LuAG:Pr and YAG:Pr SCFs phosphors, grown from Bi2O3 flux, is observed due to the quenching influence of Bi3+ flux related impurity. Due to overlap of the UV emission band of Bi3+ centers with the f–d absorption bands of Pr3+ ions in the UV range and the luminescence of excitons localized around Bi ions with the f–f absorption bands of Pr3+ ions in the visible range, an effective energy transfer from Bi3+ ions to Pr3+ ions takes place in LuAG:Bi,Pr and YAG:Bi,Pr SCFs, resulting in the appearance of slower component in the decay kinetics of the Pr3+ d–f luminescence.
•Bi and Pr doped film phosphor grown by liquid phase epitaxy method.•Energy transfer from Bi3+ to Pr3+ ions.•Strong quenching of the Pr3+ luminescence by Bi3+ co-dopant.
Scintillator-based X-ray imaging is a powerful technique for noninvasive realspace microscopic structural investigation such as synchrotron-based computed tomography. The resolution of an optical ...image formed by scintillation emission is fundamentally diffraction limited. To overcome this limit, stimulated scintillation emission depletion (SSED) X-ray imaging, based on stimulated emission depletion (STED) microscopy, has been recently developed. This technique imposes new requirements on the scintillator material: efficient de-excitation by the STED-laser and negligible STED-laser excited luminescence. In this work, luminescence depletion was measured in several commonly-used Ce3+, Tb3+, and Eu3+ -doped scintillators using various STED lasers. The depletion of Tb3+ and Eu3+ via 4f-4f transitions was more efficient (P-s = 8.. 19 mW) than Ce3+ depletion via 5d-4f transitions (P-s = 43.. 45 mW). Main origins of STED-laser excited luminescence were one-and two-photon excitation, and scintillator impurities. LSO: Tb scintillator and a 628 nm cw STED-laser is the most promising combination for SSED satisfying the above-mentioned requirements. (C) 2017 Optical Society of America
This paper presents selected optically stimulated luminescence properties of Lu2SiO5:Ce single crystalline films grown using Liquid Phase Epitaxy technique. Comparison of continuous wave optically ...stimulated luminescence decay curves under blue and green light stimulation is shown. The dose response characteristic is found to be linear in the studied range from 100 μGy to 1 Gy. Analyses of the linearly modulated optically stimulated luminescence signal enabled establishing of the photoionization cross sections for blue light (470 nm). Bleachability and thermal stability of CW–OSL signal are discussed, as well as preliminary results of the fading study.
•LSO:Ce CW–OSL decay curves under blue and green light stimulation are presented.•Determination of LSO:Ce components' photoionization cross sections for blue light.•LSO:Ce CW–OSL signal bleachability and thermal stability was studied.•LSO:Ce OSL dose response characteristic is shown.•Presentation of LSO:Ce preliminary OSL fading studies.
The aim of the study was to describe the use of the wound analgesia method in a patient with hemophilia in the case of a clinical case.
A patient with severe hemophilia A underwent postoperative ...analgesia after total knee replacement (within the first 48 hours) with an extended infusion of local anesthetic (ropivacaine) into the wound.
During the first 8 hours, the patient received 20 mg of morphine (with the aid of a device for patient-controlled analgesia), the pain level ranged from 7 to 4 points. Further, there was a sufficient effect (NRS - 2 points), from anesthesia only with ropivacaine, using a system for anesthetizing surgical wounds. Complications and side effects were not noted.
The clinical case demonstrates an effective and safe method of prolonged analgesia in patients with hemophilia. Considering encouraging data, further study of wound analgesia in this category of patients is necessary.
PDF
