Определение мёртвого времени детектора при исследовании состава изотопно-обогащённых растворов меди ⁶⁵Cu и цинка ⁶⁸Zn

При измерении изотопного состава веществ и материалов с помощью квадрупольного масс-спектрометра с индуктивно связанной плазмой основным источником искажений измеренных изотопных отношений является мёртвое время детектора. В связи с этим важными этапами процесса разработки стандартных образцов изотопного состава являются определение значений мёртвого времени детектора и соответствующая коррекция полученных результатов. Рассмотрены три метода определения мёртвого времени, основанные на измерениях изотопных отношений ⁶³Cu/⁶⁵Cu, ⁶⁴Zn/⁶⁸Zn, ⁶⁶Zn/⁶⁸Zn, ⁶⁷Zn/⁶⁸Zn, ⁷⁰Zn/⁶8Zn в растворах меди и цинка с различными массовыми долями, а также метод сравнения импульсного и аналогового сигналов детектора квадрупольного масс-спектрометра с индуктивно связанной плазмой. Четырьмя методами исследовано влияние мёртвого времени детектора на результаты измерений изотопных отношений при определении изотопного состава растворов меди и цинка, обогащённых изотопами ⁶⁵Cu и ⁶⁸Zn соответственно. Рассчитаны неопределённости полученных значений мёртвого времени детектора указанными методами. В результате исследований выбраны наиболее точные методы определения мёртвого времени детектора – метод анализа угловых коэффициентов и метод подбора (методы 3, 4). При исследовании изотопно-обогащённого раствора ⁶⁵Cu мёртвое время детектора, полученное методом 3, составило (73±4) нс, а методом 4 – (76±4) нс. В случае изотопно-обогащённого раствора ⁶⁸Zn наиболее точным оказался метод 4, мёртвое время детектора составило (42±4) нс. Полученные результаты использованы при разработке и характеризации стандартных образцов изотопного состава растворов меди и цинка, обогащённых изотопами ⁶⁵Cu и ⁶⁸Zn

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