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Information × Registration Number 0314U004042, 0113U003996 , R & D reports Title Relaxation of high-energy electronic excitations in polymer-mineral composite materials popup.stage_title Релаксація високоенергетичного електронного збудження у полімер-мінеральних композитних матеріалах Head Voloshynovskyy Anatoliy Stepanovych, Registration Date 05-02-2014 Organization Ivan Franko National University of Lviv popup.description2 The dependence of the intrinsic luminescence intensity of CaF2, SrF2, BaF2 nanoparticles interpreted in the terms of the relation between the free mean path length of photoelectrons and electron thermalization length and nanoparticle sizes. The luminescence intensity decrease is caused by the release of thermalized elec-trons and photoelectrons from the nanoparticles. The thermalization length of elec-trons and the mean free path of photoelectrons were estimated as 100 nm and 40 nm, respectively. The electronic energy structure of CaF2, SrF2 and BaF2 crys-tals was calculated using the PAW formalism based on PBE0 GGA strong local correlation approximation. The values of effective masses of electrons in the vicin-ity of the G-point of the Brillouin zone were obtained. Using the results of energy band structure calculation the average values of electron thermalization lengths (for kinetic energy of 5 eV) were estimated as 66, 95 and 117 nm, respectively for CaF2, SrF2 and BaF2 crystals.In the case of polystyrene composites filled with nanoparticles the polystyrene scintillator luminescence is caused by the excitation of polystyrene matrix by the electrons emitted from nanoparticles. The light yield of nanocomposites is almost on two orders of magnitude higher comparing with pure polystyrene scintillator and in some cases achieves 0.7 of intensity of BaF2 bulk samples. At the same time the scintillation pulse possess the fast decay com-ponent with time constant ? = 2 ns, indicating the perspective to develop fast scin-tillators for registration of low X- and gamma quanta based on the polystyrene nanocomposites. Product Description popup.authors Антоняк О.Т. Вістовський В.В. Волошиновська О.І. Гамерник Р.В. Демків Т.М. Демченко П.Ю. Дулька Л.В. Пашук І.П. Перевізник О.Б. Хапко З.А. Чорнодольський Я.М. Якібчук П.М. popup.nrat_date 2020-04-02 Close