Creation of photostimulable centers in BaFBr:<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Eu</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>single crystals by vacuum ultraviolet radiation

Rüter, H. H.; Seggern, Heinz von; Reininger, R.; Saile, V.

doi:10.1103/physrevlett.65.2438

Cited by 88 publications

(36 citation statements)

References 12 publications

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“…The measurements were carried out using synchrotron radiation, which, due to its broad and continuous spectrum, is a very useful tool for the investigation of optical and luminescence properties of wide-band-gap materials [17][18][19][20] where UV and VUV excitations are dominant. However, it is less useful for many bulk semiconductors where band-gap transitions can be excited by visible light from standard commercial spectrometers.…”

Section: Methodsmentioning

confidence: 99%

Si nanocrystals embedded in SiO2: Optical studies in the vacuum ultraviolet range

Pankratov

Osinniy

Kotlov³

et al. 2011

Phys. Rev. B

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Photoluminescence excitation and transmission spectra of Si nanocrystals of different diameters embedded in a SiO 2 matrix have been investigated in the broad visible-vacuum ultraviolet spectral range using synchrotron radiation. The dependence of the photoluminescence excitation spectra on the nanocrystals size was experimentally established. It is shown that the photoluminescence excitation and absorption spectra are significantly blueshifted with decreasing Si nanocrystal size. A detailed comparison of photoluminescence excitation and absorption spectra with data from theoretical modeling has been done. It is demonstrated that the experimentally determined blueshift of the photoluminescence excitation and absorption spectra is larger than the theoretical predictions. The influence of point defects in the SiO 2 matrix on the optical and luminescence properties of the embedded Si nanocrystals is discussed. Moreover, it is demonstrated that no energy transfer takes place between the SiO 2 and Si nanocrystals when the excitation energy is higher than the band-to-band transition energy in SiO 2 .

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Section: Methodsmentioning

confidence: 99%

Si nanocrystals embedded in SiO2: Optical studies in the vacuum ultraviolet range

Pankratov

Osinniy

Kotlov³

et al. 2011

Phys. Rev. B

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“…[44][45][46] Most of the studies reported in the literature were performed using laser or ultraviolet lamps as an excitation sources, while, for instance, LaPO 4 belongs to the class of wideband-gap materials, and its experimental bandgap was reported to be around 8.0 eV. 47,48 To extend the excitation energy range, in this paper, we use the pulsed synchrotron radiation, which, due to its broad and continuous spectrum, is a very useful tool for the investigation of optical and luminescence properties of wideband-gap materials, [49][50][51][52][53][54] where UV and VUV excitations are dominant.…”

Section: Introductionmentioning

confidence: 99%

LaPO4:Ce,Tb and YVO4:Eu nanophosphors: Luminescence studies in the vacuum ultraviolet spectral range

Pankratov

Попов

Shirmane

et al. 2011

Journal of Applied Physics

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Comparative analysis of the luminescent properties of nanocrystalline LaPO 4 :Ce,Tb and YVO 4 :Eu luminescent materials with macrocrystalline analogues, commercially produced by Philips, has been performed under excitation by pulsed vacuum ultraviolet (VUV) synchrotron radiation, ranging from 3.7-40 eV. Special attention was paid to VUV spectral range, which is not reachable with commonly used lamp and laser sources. Our results clearly show distinct difference in the excitation spectra for nano-and macrocrystalline samples, especially at energies, when the spatial separation of electron-hole pairs is comparable with sizes of nanoparticles. Differences in the region of multiplication of the electronic excitations are also demonstrated and discussed.

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“…Clearly, there is a luminescence emission peak centered at 430 nm, which could be attributed to the recombination of F-center electrons with holes stored at the Cl 2 − V k centers, or e-V k recombination. [16][17][18][19] The electron configuration of chlorine in KCl is 3s 2 3p 6 . During x ray irradiation, one p-electron is liberated, leaving behind a hole that could subsequently be trapped by a chlorine molecular ion forming a Cl 2 − V k center.…”

Section: Resultsmentioning

confidence: 99%

Temporal signal stability of KCl:Eu²⁺ storage phosphor dosimeters

et al. 2013

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Purpose: Current KCl:Eu 2+ prototype dosimeters require a wait time of 12 h between irradiation and dosimetric readout. Although irradiating the dosimeters in the evening and reading on the following day works well in the clinical schedule, reducing the wait time to few hours is desirable. The purposes of this work are to determine the origin of the unstable charge-storage centers and to determine if these centers respond to optical or thermal excitation prior to dosimetric readout. Methods: Pellet-style KCl:Eu 2+ dosimeters were fabricated in-house for this study. A 6 MV photon beam was used to irradiate the dosimeters. After x ray irradiation, dosimeters were subjected to external excitation with near-infrared (NIR) light, ultraviolet (UV) light, or thermal treatment. Photostimulated luminescence (PSL) signal's temporal stability was subsequently measured at room temperature over a few hours using a laboratory PSL readout system. The dosimeters were also placed in a cryostat to measure the temperature dependence of the temporal stability down to 10 K. Results: Strong F-band was present in the PSL stimulation spectrum, indicating that F-centers were the electron-storage centers in KCl:Eu 2+ where an electron was stored at a chlorine anion vacancy. Due to deep energy-depth (2.2 eV), F-centers were probably not responsible for the fast fading in the first a few hours post x ray irradiation. In addition, weak NIR bands were present. However, there was no change in PSL stabilization rate with intense NIR excitation, suggesting that the NIR bands played no role in the PSL fading. At temperatures lower than 77 K there was almost no signal fading with time. Noticeable PSL was observed for undoped KCl samples at room temperature, suggesting that Cl 2 − V k centers served as hole-storage centers for both undoped and doped KCl where a hole was trapped by a chlorine molecular ion. V k centers were stable at low temperature and became mobile at room temperature, probably causing the observed PSL fading with time. On the other hand, V k center could be stabilized by Eu 2+ activator or oxygen in the lattice, leading to the stable component in the PSL. A thermal process at elevated temperatures (60• C or higher) was able to significantly accelerate the migration process resulting in a fast stabilization of PSL. However, this could not be accomplished using intense UV excitation. Conclusions: Thermal treatment enables KCl:Eu 2+ prototypes to be ready for readout in 1 h without the need of applying a large time-dependent correction factor. However, this cannot be achieved using optical preexcitation.

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Creation of photostimulable centers in BaFBr:Eu2+single crystals by vacuum ultraviolet radiation

Cited by 88 publications

References 12 publications

Si nanocrystals embedded in SiO2: Optical studies in the vacuum ultraviolet range

Si nanocrystals embedded in SiO2: Optical studies in the vacuum ultraviolet range

LaPO4:Ce,Tb and YVO4:Eu nanophosphors: Luminescence studies in the vacuum ultraviolet spectral range

Temporal signal stability of KCl:Eu²⁺ storage phosphor dosimeters

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Creation of photostimulable centers in BaFBr:Eu2+single crystals by vacuum ultraviolet radiation

Cited by 88 publications

References 12 publications

Si nanocrystals embedded in SiO2: Optical studies in the vacuum ultraviolet range

Si nanocrystals embedded in SiO2: Optical studies in the vacuum ultraviolet range

LaPO4:Ce,Tb and YVO4:Eu nanophosphors: Luminescence studies in the vacuum ultraviolet spectral range

Temporal signal stability of KCl:Eu2+ storage phosphor dosimeters

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Temporal signal stability of KCl:Eu²⁺ storage phosphor dosimeters