Magnetic enhancement for the analysis of scintillation crystals by radio frequency glow discharge mass spectrometry

Abstract

A ring magnet enhancement method was developed and utilized for boosting the signal intensity of the analysis of scintillation crystals by radio frequency glow discharge mass spectrometry (rf-GD-MS). Three scintillation crystals of BGO, LYSO and GGAG were applied to observe the performance of the ring magnet method. The investigations suggested that the signal intensities obtained for ²⁰⁹Bi, ¹⁷⁵Lu and ¹⁵⁸Gd with the ring magnet were 7810–27 600 times those obtained without a magnet and were enhanced by a factor of 1.9–2.3 compared with the previously reported stacked magnet and array magnet methods. The results also suggested that the signal intensity was enhanced as the rf power increases from 25 W to 70 W (with a frequency of 13.56 MHz) and a sharp rise up to 4.8 MPa and then decreased with the increase of discharge pressure from 2.2 to 8.4 MPa. The validation results with two NIST samples indicated that the relative errors were within 13% and the lowest detection limit could reach as low as 0.0023 μg g⁻¹ (²⁴Mg, with 40 W and 4.8 MPa) for the ring magnet. The enhancement mechanism of this method was further proposed in which electrons could undergo distinct Larmor precession with a ring magnet, which could increase the collisions between the electrons and other particles to increase the ionization efficiency. Moreover, this work not only shed light on the possible enhancement mechanism by the ring magnet but also provided an effective determination method for the artificial crystals.