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Intratrack rediolytic processes studied by positron annihilation and emission Mössbauer spectroscopiesтезисы доклада
- Авторы: Stepanov S.V., Byakov V.M., Perfiliev Yu D., Kulikov L.A.
- Сборник: International Conference on the Applications of the Mossbauer Effect ICAME 2015 - Book of Abstracts
- Тезисы
- Год издания: 2015
- Место издания: Hamburg, Germany
- Первая страница: 1
- Последняя страница: 364
- Аннотация: Intratrack rediolytic processes studied by positron annihilation and emission Moessbauer spectroscopies S.V. Stepanov1,2 *, V.M. Byakov1,3, Yu.D. Perfiliev4 and L.A. Kulikov4 1 Institute for Theoretical and Experimental Physics, B. Cheremushkinskaya, 25, 117218, Moscow, Russia 2 National Research Nuclear University "MEPhI", Kashirskoye shosse 31, 115409, Moscow, Russia 3 D. Mendeleyev University of Chemical Technology of Russia, Miusskaya sq., 9, 125047, Moscow, Russia 4 Lomonosov Moscow State University, Chemical Department, GSP-1, Leninskie Gory, 119991, Moscow, Russia Intratrack chemical reactions in frozen solutions can be studied by means of the emission Moesbauer spectroscopy (EMS). Radioactive transformation of 57Co into 57Fe (E-capture by 57Co nucleolus) is accompanied by emission of several Auger-electrons having total kinetic energy about 6 keV. Emission of these energized electrons leads to formation of a cloud around Moessbauer 57Fe ion with a radius of about 100 Å containing (200-300) ion-electron pairs (H2O+, e- in case of aqueous solutions). Such a cloud (the Auger-blob [1]) is formed within 10-13 s. Further fast intrablob processes (ion-electron recombination, electron localization and scavenging) can be observed experimentally via measuring of the yields of final chemically stable ions 57Fe3+ and 57Fe2+ by means of EMS. Observation of these processes is terminated by the lifetime of the excited Moessbauer nuclei 57Fe, which is about 10-7 s. We have studied experimentally reaction ability of NO3- cations towards quasifree track electrons in frozen aqueous solutions of acids and salts [1]. It was shown that NO3- scavenges track electron more efficiently than H3O+, but only by a factor of 3. It is in a drastic contradiction with known behavior of nitrite ions in liquid water, where they are very efficient electron scavenger. Quite similar processes take place in the terminal part of the track of a fast positron (e+) ingected into a molecular medium. There are several steps of the e+ evolution before its annihilation [2]: 1) ionization slowing down, thermalization, formation of a positron track and its terminal part (blob), electrostatic interaction between e+ and radiolytic products in its blob, effect of local heating; 2) positronium formation in condensed molecular media, formation of the Ps bubble in liquids; 3) intratrack diffusion-controlled reactions of Ps with radiolytic products at different temperatures. References [1] S.V. Stepanov, V.M. Byakov, Yu.D. Perfilev, L.A. Kulikov Bulletin of the Russian Academy of Sciences. Physics, Vol. 77, No. 6, pp. 770-774 (2013) [2] S.V. Stepanov, V.M. Byakov, D.S. Zvezhinskiy et al., Advances in Physical Chemistry, vol. 2012, Article ID 431962, (2012) *) stepanov@itep.ru
- Добавил в систему: Перфильев Юрий Дмитриевич