| Маркер записи | n 22 3 4500 |
| Контрольный номер | uchm18_to87_no8_ss727_ad1 |
| Дата корректировки | 13:47:36 13 мая 2025 г. |
| Кодируемые данные | 181015s2018||||RU|||||||||||#||||# rus0| |
| Системный контрольный номер | RUMARS-uchm18_to87_no8_ss727_ad1 |
| AR-MARS | |
| Служба первич. каталог. |
Научная библиотека Чувашского государственного университета МАРС BY-HM0026 |
| Код языка каталог. | rus |
| Код языка издания |
eng eng |
| Индекс УДК |
544 543.4/.5 |
| Индекс ББК |
24.5 24.46/48 24.5 24.46/48 |
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Таблицы для массовых библиотек Таблицы для массовых библиотек Таблицы для массовых библиотек Таблицы для массовых библиотек |
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Buchachenko, A. L. professor z01710 070 |
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Magnetic isotopes as a means to elucidate Earth and environmental chemistry [Текст] A. L. Buchachenko |
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| Иллюстрации/ тип воспроизводства | 13 рис., 13 схем |
| Библиография | Библиогр.: с. 739-740 (92 назв. ) |
| Аннотация | In Earth and environmental chemistry, magnetic isotopes provide a universal means to identify reaction mechanisms. Mass-independent fractionation of isotopes as a signature of a mechanism occurs by two ways: first, via the magnetic isotope effect (MIE), which is controlled by magnetic, or hyperfine, coupling between unpaired electrons and magnetic nuclei in paramagnetic species (particularly, in radicals), and, second, via the nuclear volume effect (NVE), which is induced by the volume difference between isotopic nuclei. The MIE is the dependence of the reaction rates on the nuclear magnetic moment of reactants and fractionates magnetic and nonmagnetic isotopes, whereas NVE fractionates isotopes with different nuclear volumes. Both effects, MIE and NVE, are supposed to coexist in condensed phases. A decisive test for their differentiation is illustrated by the example of radical pairs with mercury nuclei. Namely, if isotope fractionation is controlled by MIE, the ratio дельта{201}Hg/дельта{199}Hg is expected to be in the range of 1. 05-1. 25 for isotopic enrichment and 0. 80-0. 92 for depletion. If isotope fractionation is controlled by NVE, this ratio is estimated to be in the range of 0. 50-0. 62. In contrast to MIE-induced bidirectional fractionation controlled by the direction of coherent spin conversion of the radical pair (triplet-singlet or vice versa), the NVE induces unidirectional, universal isotope fractionation, which is almost independent of the reaction mechanism. In contrast to MIE which exhibits inversion of the fractionation sign depending on the spin multiplicity of reactants, NVE is incompatible with the inversion of the fractionation sign. The MIE is an unambiguous indicator of the radical mechanisms and dominates in chemical reactions, whereas NVE prevails in nonchemical processes. Chemical scenarios of MIE-induced oxygen, sulfur, iron, silicon, tin, mercury, germanium and uranium isotope fractionation in photostimulated and dark reactions are analyzed in terms of reaction mechanisms including reactions in living organisms. In conclusion, some restrictions, uncertainties and problems in Earth and environmental chemistry are discussed. |
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Химия AR-MARS Физическая химия в целом AR-MARS Физико-химические методы анализа AR-MARS |
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| Ключевые слова |
изотопные ядра изотопы магнитные изотопные эффекты магнитные изотопы физика окружающей среды химия окружающей среды ядерные объемные эффекты |
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N. N. Semenov Institute of Chemical Physics z01100 Москва Вторичная ответственность Institute of Problems of Chemical Physics z01100 Москва Вторичная ответственность Science Center in Chernogolovka of the Russian Academy of Sciences z01100 Вторичная ответственность P. G. Demidov Yaroslavl State University z01100 Вторичная ответственность Lomonosov Moscow State University Department of Chemistry z01100 Вторичная ответственность |
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| ISSN | 0042-1308 |
| Название источника | Успехи химии |
| Место и дата издания | 2018 |
| Прочая информация | Т. 87, № 8. - С. 727-740 |
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RU 42813093 20181015 RCR |
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RU 42813093 20181015 |
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RU AR-MARS 20181015 RCR |
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RU AR-MARS 20181015 |
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| Тип документа | b |
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code year to no ss ad |
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uchm 2018 87 8 727 1 |
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| 244 |
