Search results for "RADIATION"
showing 10 items of 5298 documents
Glossary of terms used in photocatalysis and radiation catalysis (IUPAC Recommendations 2011)
2011
This glossary of terms covers phenomena considered under the very wide terms photocatalysis and radiation catalysis. A clear distinction is made between phenomena related to either photochemistry and photocatalysis or radiation chemistry and radiation catalysis. The term “radiation” is used here as embracing electromagnetic radiation of all wavelengths, but in general excluding fast-moving particles. Consistent definitions are given of terms in the areas mentioned above, as well as definitions of the most important parameters used for the quantitative description of the phenomena. Terms related to the up-scaling of photocatalytic processes for industrial applications have been included. Thi…
Mollwo–Ivey relations for optical absorption bands of the atomic and F′ centres in alkali halides
2001
Evidence indicates that two classes of the transient IR-absorption bands: (a) with maxima at 0.27-0.36 eV in NaCI, KCI, KBr, KI and RbCl and due to shallow electron traps or bound polarons according to Jacobs (Phys. Stat. Sol. B 129 (1985) 755) and Korovkin and Lebedkina (Fiz. Tverd. Tela (Russian) 35 (1993) 642), and (b) with maxima at 0.15-0.36 eV in NaI, NaBr, NaCl : I, KCl : I I, RbCl: I and RbBr : I, due to on-centre STE localised at iodine-dimer according to Hirota et al. (J. Phys. Soc. Japan 63 (1994) 2774, Phys. Rev. B 52 (1995) 7779) and Edamatsu and Hirai (Mater. Sci. Forum 239-241 (1997) 525), are caused by the same defect. We propose that the defect is an atomic alkali impurity …
Development of accelerator mass spectrometry assisted by isotope-selective laser photodetachment for monitoring 129I
2013
Abstract A prototype system was developed to investigate an isotope-selective laser photodetachment technique for a 129 I accelerator mass spectrometer. A pulsed ion source for negative iodine ions (I − ) that employed laser ablation proved to be suitable for isotope-selective laser photodetachment. Laser photodetachment of pulsed negative iodine ions was estimated to have an efficiency of about 81% based on a model calculation for the prototype system with a tunable pulsed Ti:sapphire laser.
Ten years of measured UV Index from the Spanish UVB Radiometric Network.
2013
An analysis is made of the UV Index (UVI) obtained from the ultraviolet erythemal solar radiation (UVER) data measured by the Spanish UVB Radiometric Network between the years 2000 and 2009. Previously, the daily UVI has been evaluated using two different criteria: (a) the value corresponding to solar noon; and (b) the daily maximum value. The mean percentage of agreement is 92% if we consider the cases for which the difference is zero or one UVI unit. These results are similar to those obtained in a previous work where only 2 years were analyzed. In all the stations the UVI reaches very high values (8-10) in spring-summer, and the very high and extreme (≥ 11) UVI values are more dependent …
Magnetooptical studies of defects and recombination luminescence in LiBaF3
2004
Abstract Optically detected EPR investigations have been performed on the recombination luminescence (RL-EPR) of LiBaF3 crystal, X-irradiated at T=4.2 K . RL-EPR lines of VK- centres were found, as well as further lines of a defect with S= 1 2 and an axial g-tensor with its main axis along a [1 0 0] direction of the crystal. Measurements of the magnetic circular dichroism of the absorption (MCDA) have been performed on LiBaF3 crystals X-irradiated at two temperatures ( 4.2 K and RT). After irradiation at T=4.2 K , the main MCDA bands peak at 453 and 500 nm , but after irradiation at T=300 K , the main bands peak at 444 and 390 nm , there is a change of the sign between the peaks in both cas…
Estimation of external gamma radiation dose in the area of Bory Stobrawskie forests (PL).
2011
The study assessed the radiological risks associated with the presence of natural and artificial radionuclides in the Bory Stobrawskie forests (PL). Using the conversion factors given by UNSCEAR and the measurements results of (232)Th series, (238)U series, (40)K, and (137)Cs specific activities in the 10-cm soil layer the values of absorbed dose (D) and the annual effective dose equivalent derived from terrestrial gamma radiation (E) were calculated. The calculated dose was compared with doses directly measured on the area studied.
Heat shrinkable behavior, physico-mechanical and structure properties of electron beam cross-linked blends of high-density polyethylene with acryloni…
2016
Abstract In this study, heat-shrinkable composites of electron beam irradiated high-density polyethylene (HDPE) composites with acrylonitrile-butadiene rubber (NBR) were investigated. HDPE/NBR blends at a ratio of components 100/0, 90/10, 80/20, 50/50 and 20/80 wt% were prepared using a two-roll mill. The compression molded films were irradiated high-energy (5 MeV) accelerated electrons up to irradiation absorbed doses of 100–300 kGy. The effect of electron beam induced cross-linking was evaluated by the changes of mechanical properties, gel content and by the differences of thermal properties, detected by differential scanning calorimetry. The thermo-shrinkage forces were determined as the…
Evidence for a critical dose above which damage to carbonate ester bonds in PADC appear after gamma ray and ultra soft X-ray exposures
2020
Abstract It has been confirmed that the density of carbonate ester in poly(allyl diglycol carbonate) (PADC), which is a well-known polymeric nuclear track detector CR-39, begins decreasing above a critical dose of about 60 kGy during exposures to Co-60 gamma rays and Ultra Soft X-rays (USX: Kα (Al) with energy 1.49 keV). After exposure to Co-60 gamma rays at 77 K and room temperature (RT), a significant difference in Electron Spin Resonance (ESR) spectra has been observed at both sides of a critical dose of 60 kGy, where is a threshold for the degradation of carbonate ester in PADC. Namely, the types of free radicals in PADC are different from each other below and above this critical dose. …
Dyadic Green's function for the electrically biased graphene-based multilayered spherical structures
2020
Abstract Dyadic Green's function for a multilayered spherical structure with alternating graphene-dielectric shells is extracted in this paper. To this end, the unknown expansion coefficients of the scattering superposition method are obtained by considering graphene local surface currents at the interface of two adjacent layers. To validate the formulas, the procedure of Mie scattering analysis employing our formulas is clarified and the extinction efficiencies of various graphene-based nanoparticles are computed. The possibility of using the proposed structure in the design of multi-band optical absorbers is discussed in detail. Moreover, a closed-form formula for obtaining the Purcell fa…
Speed-dependent broadening and line mixing in CH4 perturbed by Ar and N2 from multispectrum fits
2000
International audience; Speed-dependent broadenings and shifts have been determined for the P and R branches of the nu3 band of CH4 perturbed by Ar and N2 using a multispectrum fitting analysis of high-resolution tunable difference-frequency laser spectra recorded at pressures 3, the tetrahedral fine structure components in each J manifold are collisionally coupled and exhibit significant interference. The coupled lines are treated using a speed-dependent first-order line-mixing profile and are compared to a speed-independent full relaxation matrix inversion procedure with off-diagonal coupling elements calculated from an atom-atom Lennard-Jones potential model.