Positive ion mass spectrometry 14C measuring method and positive ion mass spectrometry device

Abstract

The invention provides a positive ion mass spectrometry 14C measuring method and a positive ion mass spectrometry device, and belongs to the technical field of accelerator mass spectrometry. The device comprises a 2.45 GHz ECR ion source, a non-metal gas charge exchanger, a solenoid, an analysis system and a particle detector which are connected in sequence, the 2.45 GHz ECR ion source generates C2 + ions, and the non-metal gas charge exchanger selects one or a mixture gas of isobutane, isobutene, ethylene, propylene, propyne, allene, butylene and 1, 3-propylene as a charge exchange target, C2 + ions generated by an ion source are converted into C-ions, focusing is performed on a C-ion beam formed after charge exchange by a solenoid, and the C-ion beam is sent the focused C-ion beam into an analysis magnet; the analysis magnet is used for separating 12C-, 13C- and 14C- ions; 12C- and 13C- are measured through a bias Faraday cup behind an analysis magnet; 14C- ions enter the particle detector through the electrostatic analyzer to be measured, and finally the ratio of 14C to 12C or 13 C is obtained. According to the invention, high-precision measurement of 14C can be realized.

Description

technical field [0001] The invention belongs to the technical field of accelerator mass spectrometry (AMS), in particular to a positive ion mass spectrometer based on a 2.45GHz ECR strong current positive ion source and a non-metallic gas charge exchanger and a corresponding positive ion mass spectrometer 14 C measurement method. Background technique [0002] Accelerator mass spectrometry (AMS), as an ultra-high sensitivity mass spectrometry technique, plays an irreplaceable role in the measurement of radionuclides, and is widely used in the research of the atmosphere, biosphere, hydrosphere, cryosphere, lithosphere and cosmic nuclides ,and 14 C is the most important and commonly used nuclide measured by AMS, accounting for more than 90% of the samples measured by AMS. Among the isotopes of C, the stable isotopes 12 C accounts for 98.9%, stable isotope 13 C accounts for 1.1%, radioactive isotope 14 C ratio is 10 -12 or less. Therefore to achieve 14 The measurement of...

AI Technical Summary

Problems solved by technology

There are still two types of problems: one is that the Cs sputtering negative ion source uses graphite samples to form C - ions, and the sample preparation process of graphite samples is extremely complicated, the sample preparation requires strong professionalism, and the pollution control of sample preparation is difficult

The current PIMS concept system is still in the stage of verification and exploration, and all laboratories use high-frequency ECR ion sources to generate C 2+ / C 3+ Ion, the cost of ion source is still very high; C 2+ 、C 3+ The mechanism of charge exchange is unclear, and there is still no consistent consensus on the choice of charge exchange target

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