Minimising 12 C 3+ interference on 4 He + measurements in a noble gas mass spectrometer
Minimising 12 C 3+ interference on 4 He + measurements in a noble gas mass spectrometer
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最大限度地减少 12 C 3 对惰性气体质谱仪中 4 He 测量的干扰
DOI：
10.1039/c4ja00422a
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发表时间：
2015
影响因子：
3.4
通讯作者：
Schwanethal J
中科院分区：
文献类型：
--
作者：
Schwanethal J
用于地质年代学研究的氦同位素测量易受12 C3+和HD+的干扰。在Nu Instruments Noblesse质谱仪上研究了12 C3+干扰，该质谱仪具有足够的质量分辨率，通过将磁体设置在相关峰肩处，直接测量由于12 C3+对4 He+峰的干扰。氦灵敏度随源阱电流而变化。增加源阱电流会增加电子注量，从而增加源内电离的可能性。Noblesse上的源极陷阱电流通常保持在400 μA。将陷阱电流增加到550 μA，对4 He+的灵敏度增加约2倍，但对12 C3+的灵敏度增加约17倍。尽管质量分辨率高，但m/z = 4处的4 He+和12 C3+峰肩较窄，因此任何仪器漂移都可能导致峰位丢失。然而，它表明，在m/z = 6处的12 C2+的测量可以用于校正这种干扰，允许使用m/z = 4的宽平顶的强度。
Measurements of helium isotopes used for geochronological studies are subject to interferences from 12C3+ and HD+. The 12C3+ interference was studied on a Nu Instruments Noblesse mass spectrometer which has sufficient mass resolution to measure the interference on the 4He+ peak due to 12C3+ directly, by setting the magnet at the relevant peak shoulders. Helium sensitivity varies with source trap current. Increasing the source trap current increases the electron fluence, and hence the probability of ionisation, within the source. The source trap current on the Noblesse is typically held at ∼400 μA. Increasing the trap current to 550 μA increases sensitivity to 4He+ approximately two-fold, but 12C3+ increases approximately 17 times. The 4He+ and 12C3+ peak shoulders at m/z = 4 are narrow, despite the high mass resolution, and consequently any instrument drift can cause the peak positions to be lost. However, it is shown that measurement of 12C2+ at m/z = 6 can be used to correct for this interference, allowing the intensity of the broad flat top of m/z = 4 to be used.