Self-quenching effects of excitons in CaWO4 under high density XUV free electron laser excitation

Vielhauer, S.; Babin, V.; Grazia, M. De; Feldbach, E.; Kirm, M.; Nagirnyi, V.; Vasil’ev, A. N.

doi:10.1134/s1063783408090394

Cited by 16 publications

(14 citation statements)

References 12 publications

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“…Comparing the three emission spectra measured for different average pulse energies, no significant changes in the structure of the bands were observed. This corresponds to similar findings in CaWO 4 and CdWO 4 [2] with the exception that in the case of CaWO 4 , a weak band of impurity-related defect emission at around 600 nm was observed. This defect band showed signs of saturation under higher pulse energies, which can easily be explained by the comparably low concentration of impurities in the crystal.…”

Section: Methodssupporting

confidence: 67%

“…The observed deviation from a single exponential decay behavior in the initial part of the decay curves in CaWO 4 and CdWO 4 under high excitation densities has been explained by the model of excitonic self-quenching [2][11]. The model is described in detail in these references, and will be only briefly introduced here.…”

Section: Self-quenching Of Excitonsmentioning

confidence: 99%

“…When used under these conditions, e.g. in detectors for beam diagnostics or experimental setups, the response characteristics and long-term stability need to be known to allow for accurate measurements [2] [3]. In a first step to study these factors for various phosphors, we investigated time-resolved photoluminescence for various wide band-gap materials with both intrinsic (excitonic) luminescence, and extrinsic emission from trivalent rare earth ions (RE 3+ ) doped into the crystal.…”

Section: Introductionmentioning

confidence: 99%

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Phosphor materials under high-density XUV FEL excitation: mechanisms of luminescence quenching

et al. 2009

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Photoluminescence of scintillator materials based on intrinsic excitonic luminescence (PbWO 4 ), and on extrinsic luminescence from doped trivalent rare earth ions (RE 3+ ), such as Y 3 Al 5 O 12 :Ce 3+ and Lu 3 Al 5 O 12 :Pr 3+ was studied under excitation with free electron laser (FEL) light in the 50-100 eV energy range. In case of PbWO 4 , non-exponential behavior in the initial part of decay curves was observed depending on the FEL pulse energy, and modeled in terms of the bimolecular self-quenching process. For the RE 3+ doped samples, a reduction in light yield with increasing pulse energy is observed, which can be traced to saturation of the available RE 3+ sites in the crystal due to the initial high concentration of electron-hole pairs after FEL excitation.

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Section: Methodssupporting

confidence: 67%

Section: Self-quenching Of Excitonsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Phosphor materials under high-density XUV FEL excitation: mechanisms of luminescence quenching

et al. 2009

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“…2 are modelled using this theoretical approach. Quantitative results on the behaviour of different scintillators and luminescent materials under powerful FEL excitation will be presented in more detail elsewhere [10].…”

Section: Article In Pressmentioning

confidence: 99%

Behaviour of scintillators under XUV free electron laser radiation

Kirm

Babin

Feldbach

et al. 2008

Journal of Luminescence

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Free electron lasers (FEL) are new generation accelerator-based short wavelength light sources providing high pulse intensity and femtosecond pulse duration, which enable investigation of interaction of elementary excitations in solids under extreme conditions. Using the FLASH facility of HASYLAB at DESY (Hamburg, Germany), we investigated the response of different materials with scintillating properties based on intrinsic emissions to the 25.6 and 13.8 nm FEL radiation by means of time-resolved luminescence spectroscopy. FLASH delivered single pulses of 25 fs duration having energy per pulse up to 30 mJ resulting in power densities of 10 12 W/cm 2 on crystals. As a function of excitation density we observed the shortening of lifetime and non-exponential behaviour of emission decays in CaWO 4 , while the emission spectra recorded are comparable to those obtained at conventional excitation sources. r 2007 Elsevier B.V. All rights reserved.Keywords: Free electron laser; XUV radiation; Scintillators; Luminescence decay; Excitation density effects; CaWO 4Free electron lasers (FEL) are new generation accelerator-based short wavelength light sources with advanced properties (high pulse intensity, femtosecond pulse duration, monochromatic radiation, coherence, etc.), enabling new kinds of investigations in different scientific fields under extreme conditions. A pioneering test-experiment at TTF-1 facility in Hamburg had shown that interaction of 89 nm FEL radiation with scintillators leads to a remarkable shortening of the decay time and a drop in quantum yield of luminescence (e.g., in BaF 2 and YAG:Ce) [1]. Analogous observation was reported for a number of inorganic scintillators in Ref. [2], where polychromatic hard X-ray synchrotron radiation was applied in experiments. It is obvious that, due to increasing peak power of new light sources, scintillator screens leave the region of linear response, in which they have been used so far to visualise intense radiation and particle beams. In the nonlinear regime effects arising from mutual interaction of elementary excitations can be investigated in more detail in comparison with conventional radiation sources as discussed in Ref. [3].Using the BL1 of the FLASH facility of HASYLAB at DESY (Hamburg, Germany) [4], we investigated the response of different scintillation materials based on intrinsic or activator emission to 25.6 and 13.8 nm FEL radiation in single bunch mode with a pulse duration of 25 fs and maximum energy of 30 mJ at 5 Hz repetition rate. By applying a N 2 gas absorber, the incident beam could be attenuated up to two orders of magnitude from the estimated maximum value of 10 12 W/cm 2 . Luminescence spectra, typically averaged over 2000 FEL pulses, were recorded with a CCD camera mounted on the exit arm of the ARC SpectraPro308i imaging spectrograph. Emission spectra are presented as recorded without any correction to the sensitivity of detector and transmission of spectrograph. A XP2020Q PMT connected to a digital scope was used to record luminesc...

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“…However, in insulators, where only a small radius of self-trapped excitons can be observed at room temperature, much higher densities of electronic excitations are required. Modern coherent sources of radiation such as free electron lasers, powerful tuneable amplified laser systems or those based on high-order harmonic generation are capable of creating electronic excitations at densities up to 10 21 cm 3 in about 10 −13 s. By using such sources the interaction of electronic excitations has been revealed in a sequence of wide band-gap crystals and a Förster theory based model has been developed for describing luminescence yield and decay kinetics in the conditions of crystal excitation by ultra-short high-intensity laser pulses [4][5][6]. However, recent experiments have shown that un-der the conditions of excitation by intense sub-picosecond monochromatic pulses the effective absorption coefficient of CsI crystals becomes dependent on pulse energy [7].…”

Section: Introductionmentioning

confidence: 99%

Modelling of decay kinetics of self-trapped exciton luminescence in CdWO4 under femtosecond laser excitation in absorption saturation conditions

et al. 2012

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Abstract:The analytical expressions for the three-dimensional spatial distribution of excitons and luminescence decay kinetics of wide band-gap crystals were derived taking into account the saturation effect for absorption near the centre of the incident laser beam with Gaussian transversal profile. The model is verified for the excitonic emission of CdWO 4 crystals under excitation by ultra-short laser pulses in the region of weak excitonic absorption. 78.55.Hx, 78.47.jd, 71.35.Gg, 42.50.Md PACS (2008): Keywords:exciton-exciton interaction • dipole-dipole interaction • excitation density effects • absorption saturation © Versita Sp. z o.o.

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Self-quenching effects of excitons in CaWO4 under high density XUV free electron laser excitation

Cited by 16 publications

References 12 publications

Phosphor materials under high-density XUV FEL excitation: mechanisms of luminescence quenching

Phosphor materials under high-density XUV FEL excitation: mechanisms of luminescence quenching

Behaviour of scintillators under XUV free electron laser radiation

Modelling of decay kinetics of self-trapped exciton luminescence in CdWO4 under femtosecond laser excitation in absorption saturation conditions

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