Advanced instrumentation for accelerator mass spectrometry

加速器质谱仪(AMS)的优点是，可以在亚毫克样品中测量同位素和稀有原子，灵敏度接近十亿分之一，但主要局限于容易产生负离子的元素和具有不产生负离子的同素素体的元素，如碳-14和碘-129。对于不满足其中一个或两个条件的元素，分析策略的发展一直受到限制，而且往往局限于使用更大的加速器(&gt；5 mV)。IsoTrace实验室最近开始的两项创新表明，AMS的使用可以扩展到元素周期表中更大的一部分。它们是：(I)使用氟化物分子阴离子来增加AMS所需负离子的产生；(Ii)在冷却和反应池中使用射频四极离子导向器，以极低的能量消除原子和分子等压素--统称为阴离子等离子分离器(ISA)。

The advantages of accelerator mass spectrometry (AMS), in which isotopes and rare atoms can be measured in sub-milligram samples with sensitivities approaching 1 part in a thousand million million, have been largely confined to elements which readily make negative ions and which have isobars that do not, such as Carbon-14 and Iodine-129. For elements that do not meet one or both of these conditions, the development of analytical strategies has been limited and often been confined to the use of larger accelerators (>5 MV). Two innovations begun recently at the IsoTrace Laboratory have demonstrated that the use of AMS can be extended to a much larger fraction of the periodic table. These are: (i) the use of fluoride molecular anions to enhance the production of the negative ions required for AMS and (ii) the use of radio-frequency quadrupole ion guides in cooling and reaction cells to eliminate both atomic and molecular isobars at very low energies - collectively known as the Isobar Separator for Anion (ISA).