On-line I^{鈭?/sup>/Te鈭?/sup> separation for the AMS analysis of 125I}

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• 作者：C.R.J. Charles^a ; ^{christopher.charles@uottawa.ca" class="auth_mail" title="E-mail the corresponding author} ; R.J. Cornett^a ; X.-L. Zhao^a ; A.E. Litherland^b ; W.E. Kieser^a
• 关键词：Tellurium ; Iodine ; ISA ; AMS ; 125I
• 刊名：Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
• 出版年：2015
• 出版时间：15 October 2015
• 年：2015
• 卷：361
• 期：Complete
• 页码：189-192
• 全文大小：437 K

文摘

The isobar separator for anions (ISA) was used together with a 3 MV tandem accelerator mass spectrometer (AMS) to demonstrate the real time (on-line) separation of Te⁻ from I⁻. Following the ion source mass spectrometry and major retardation to tens of eV, the ISA uses a radiofrequency quadrupole (RFQ) ion guide to confine and direct I⁻ and associated Te⁻ isobar anions through a gas-reaction cell, where chemical reactions occur at eV energies with the electronegative gas NO₂. Anions are subsequently reaccelerated out of the ISA to near original ion source extraction energies for AMS analysis. At 5 mTorr NO₂ in the ISA gas-reaction cell, ¹²⁵Te⁻ was observed to be attenuated by a factor of ∼10⁷ as compared to ¹²⁷I⁻ that did not experience significant (<50%) losses. A comparative test using ³⁷Cl⁻ and ³²S⁻ (having similar chemical properties to iodine and tellurium) showed a ³²S⁻ attenuation of >10⁷ relative to ³⁷Cl⁻ under the same ISA–AMS conditions. The preferential destruction of Te⁻ (and S⁻) at eV energies in the ISA is likely due to a larger favorable destruction cross-section with NO₂. This study is the first demonstration of I–Te anion separation for AMS, and makes possible the use of ¹²⁵I, free of the contaminant ¹²⁵Te isobar after suitable sample purification, for future ¹²⁹I/¹²⁵I carrier-free analyses of natural samples at ultra-low trace levels.