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Color-center formation and thermal recovery in X-ray and electron-irradiated magnesium aluminate spinel
摘要： We have studied the formation of color centers in magnesium aluminate spinel (MgAl2O4) by X-ray and electron irradiations near room temperature (RT). For this purpose, Cu Kα radiation and three electron energies (1.0, 1.4, and 2.5 MeV) were used for variable fluences (up to 4.2 × 10^18 cm^?2). Off-line UV-visible absorption spectra were recorded at RT as well as at low temperature down to 27 K after electron irradiation. The dependence of the production rate of F centers (oxygen vacancies) on the electron energy yields a threshold displacement energy of 190 ± 10 eV for oxygen atoms at RT, which is much higher than the determinations by molecular-dynamics simulations. Such a discrepancy is discussed on the basis of available migration data of point defects in spinel. Equipartition of F0 and F+ centers, i.e., the neutral (VO^x) and singly ionized (VO^.) oxygen vacancies, is reached for high electron fluences. Moreover, the evolution of the width of color-center absorption bands versus temperature is interpreted with the classical theory for F centers (neutral halogen vacancies) in alkali halides. The Stokes shifts are deduced from the temperature dependence of the absorption bandwidths of color centers like for alkali halides and alkaline-earth oxides. Finally, isothermal annealing data for long annealing time show a non-zero asymptotic behavior for both F0 and F+ centers. This uncommon behavior is interpreted by charge exchange processes leading to an equilibrium state between those two color centers.
关键词： thermal recovery,X-ray irradiation,color centers,threshold displacement energy,F centers,electron irradiation,absorption spectroscopy,magnesium aluminate spinel
更新于2025-09-23 15:23:52
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In-Situ Measurement of Outgassing Generated from EUV Metal Oxide Nanoparticles Resist During Electron Irradiation
摘要： In this study, we prepared the EUV metal resist, which included ZrO2 nano-particle and three type ligands as 2-methyl-2-propenoic acid (MAA), 2-methylpropanoic acid (IBA) and vinylbenzoic acid (VBA). Each resist was prepared by blending each material separately for evaluating the outgassing from EUV resist materials. We prepared three-type samples of ZrO2-MAA, ZrO2-IBA and ZrO2-VBA by coating each resist, and evaluated the outgassing from these samples during irradiation of 2 keV electron by in-situ mass spectrometry. From the results of mass spectrum, we could observe the outgassing of PAG as unique peaks. And each ligand peak was distributed over the low mass range. On the other hand, the ZrO2 peaks could not be observe in mass spectrum of each sample. Thus, we guess that ZrO2 nano-particles might not be evaporating during 2 keV electron irradiation.
关键词： Ligand,EUV metal resist,Electron irradiation,Mass spectrometry,In-situ outgas measurement,ZrO2
更新于2025-09-23 15:22:29
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Fluorescent Nanodiamonds || Producing Fluorescent Nanodiamonds
摘要： Natural diamonds in colors are commonly known as fancies, or fancy color diamonds, in gemstone industries. They are rare, beautiful, and some even carry impressive price tags in the jewelry market. By comparison, micro‐ and nanoscale diamond powders are low in price, with or without colors and fluorescent or not. These powders have been used as abrasives for grinding and polishing purposes since ancient time, mainly because of their extraordinary hardness. Little or no attention has been paid over the centuries to other properties of nanodiamonds such as their innate biocompatibility and light‐emitting capability. The invention of fluorescent nanodiamond (FND) in 2005 has revolutionized the field, opening a new area of research and development with diamonds. Experiments with FNDs in the last decade have demonstrated various promising applications of surface‐functionalized FNDs in diversified fields, ranging from physics and chemistry to biology and medicine. It is worthy of noting that as originated from the discovery of Radium by Marie Sk?odowska Curie (Section 3.2), FNDs may very well be called Madame Curie’s gemstones, valued appropriately as a scientist’s best friend.
关键词： fluorescent nanodiamonds,magnetically modulated fluorescence,fluorescence lifetime,size reduction,FND,ion irradiation,H3 centers,nitrogen-vacancy centers,electron irradiation,NV centers
更新于2025-09-23 15:21:01
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Ion Implantation - Research and Application || MeV Electron Irradiation of Ion-Implanted Si-SiO2 Structures
摘要： The effect of (10–25) MeV electron irradiation on Si‐SiO2 structures implanted with different ions (Ar, Si, O, B, and P) has been investigated by different methods, such as deep‐level transient spectroscopy (DLTS), thermo‐stimulated current (TSCM), Rutherford backscattering (RBS), and soft X‐ray emission spectroscopy (SXES). It has been shown that in double‐treated Si‐SiO2 structures, the defect generation by high‐energy electrons depends significantly on the location of preliminary implanted ions relative to the Si‐SiO2 interface as well as on the type (n‐ or p‐Si) of silicon wafer. SiO2 surface roughness changes, induced by ion implantation and high‐energy electron irradiation of Si‐SiO2 structures, are observed by the atomic force microscopy (AFM). Si nanoclusters in SiO2 of ion‐implanted Si‐SiO2 structures generated by MeV electron irradiation is also discussed.
关键词： ion implantation,Si nanoclusters,MeV electron irradiation,Si‐SiO2 structures,radiation defects
更新于2025-09-23 15:19:57
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Controlling the fluorescence properties of nitrogen vacancy centers in nanodiamonds
摘要： Controlling the fluorescence properties of nitrogen vacancy centers in nanodiamonds is an important factor for their use in medical and sensor applications. However, reports providing a deep understanding of the potential factors influencing these properties are rare and focus only on a few influencing factors. The current contribution targets this issue and we report a comprehensive study of the fluorescence properties of NVs in nanodiamonds as a function of electron irradiation fluence and surface termination. Here we show that process parameters such as defect center interactions, in particular, different nitrogen defects and radiation induced lattice defects, as well as surface functionalities have a strong influence on the fluorescence intensity, fluorescence lifetime and the charge state ratio of the NV centers. By employing a time-correlated single photon counting approach we also established a method for fast macroscopic monitoring of the fluorescence properties of ND samples. We found that the fluorescence properties of NV centers may be controlled or even tuned depending upon the radiation treatment, annealing, and surface termination.
关键词： fluorescence lifetime,charge state ratio,nanodiamonds,surface termination,nitrogen vacancy centers,fluorescence properties,electron irradiation
更新于2025-09-19 17:15:36
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Structural, morphological and 6 MeV energy electron dosimetric properties of Cu doped SnO<sub>2</sub> phosphor.
摘要： Cu doped SnO2 (SnO2:Cu) nano phosphor (NP) was successfully synthesized by one-step simple hydrothermal method and it was characterized by XRD (X-Ray Diffraction) for structural, FESEM (Field Emission Scanning Electron Microscopy) for morphological and EDS (Electron Dispersive Spectroscopy) for elemental analysis. NP was annealed at 700 °C for 2 hr and its crystallinity for tetragonal phase was confirmed through XRD. The crystallite size was ~10.39 nm for un-annealed and ~18.16 nm for annealed samples which has been calculated using Scherer equation. The particle size was estimated to be ~43 nm and the elemental composition of Sn, O, Cu was obtained by EDS. In addition, to study the dosimetric properties, the SnO2:Cu phosphors were irradiated with 6 MeV electron beam at fluences ranging from 10 x 10^11 e/cm^2 to 20 x 10^12 e/cm^2 which is equivalent to the 1.55 kGy to 31 kGy. The irradiated sample showed Thermoluminescence (TL) dosimetric glow peaks at 170 °C, 263 °C and 303 °C. SnO2:Cu NP was found to be sensitive enough for energetic electrons. Further, it has been noticed that the TL dose response found sensitive upto 10 x 10^12 e/cm^2 (15.50 kGy) with fading of 5.1 % for 2 months. Hence, SnO2:Cu can be used for the measurement of electron doses.
关键词： Hydrothermal Method,Electron Irradiation,Thermoluminescence,SnO2
更新于2025-09-19 17:15:36
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Radiation Effects in Materials || Effects of Electron Irradiation Upon Absorptive and Fluorescent Properties of Some Doped Optical Fibers
摘要： A review of the recent studies of the effect of irradiating silica-based fibers doped with rare earths and metals by a beam of high-energy (β) electrons is presented. Of the review’s main scope are the attenuation spectra’ transformations occurring in optical fiber of such types under electron irradiation, allowing, from one side, to recover some general essence of the phenomena involved and, from the other side, to draw the features that would make such fibers useful for applications, for example, in dosimetry and space technologies. Among the fibers of the current review’s choice, exemplifying the effect of electron irradiation most brightly, are ytterbium (Yb) and cerium (Ce) (the rare earths’ representatives) and bismuth (Bi) (the post-transitional metals representative) doped fibers, where a diversity of the electron-irradiation-related effects is encouraged.
关键词： optical bleaching,photodarkening,cerium- and bismuth-doped silica fibers,electron irradiation,ytterbium-
更新于2025-09-16 10:30:52
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Analysis of 1?MeV electron irradiation-induced performance degradation in the germanium bottom cell of triple-junction solar cells using temperature-dependent photoluminescence measurements
摘要： Temperature-dependent photoluminescence spectra of the germanium bottom cell of triple-junction solar cells unirradiated and irradiated with 1 MeV electrons were measured in the 10–300 K temperature range. In unirradiated germanium bottom cell, the spectra show that the PL intensity increases with temperature but slightly decreases at around 250 K because of the intrinsic defect. However, in irradiated germanium bottom cell, the spectra show that there are two negative thermal quenching processes (10–90 K and 200–270 K) and two usual thermal quenching processes (90–200 K and 270–300 K) as a result of the radiation-induced defects Ec (cid:1) 0.37 eV and Ec (cid:1) 0.12 eV.
关键词： Electron irradiation,germanium bottom cell,thermal quenching,temperature-dependent photoluminescence
更新于2025-09-11 14:15:04
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Temperature-dependent photoluminescence processes of GaInP top cell irradiated with 11.5?MeV and 1.0?MeV electrons
摘要： The effects of 11.5 MeV electrons irradiation on the GaInP top cell of GaInP/GaAs/Ge triple-junction solar cells have been investigated by temperature-dependent photoluminescence (PL) measurements. The thermal quenching of PL intensity is observed in the temperature range of 10 K–270 K, attributing to the nonradiative recombination centers H2 (Ev + 0.55 eV) hole trap and H3 (Ev + 0.76 eV) hole trap. A slight negative thermal quenching (NTQ) of PL intensity exists at nearly 300 K and could be associated with the 0.18 eV intermediate states. The temperature-dependent photoluminescence process of GaInP top cell irradiated with 11.5 MeV electrons differs with that irradiated with 1.0 MeV electrons.
关键词： Photoluminescence,Electron irradiation,GaInP top cell,Negative thermal quenching
更新于2025-09-04 15:30:14