Time-of-flight MeV-SIMS with beam induced secondary electron trigger

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• 作者：Martina Schulte-Borchers ; ^{marschul@phys.ethz.ch" class="auth_mail" title="E-mail the corresponding author} ; Max Dö ; beli ; Arnold Milenko Mü ; ller ; Matthias George ; Hans-Arno Synal
• 关键词：MeV SIMS ; Secondary electrons ; Secondary ions ; Heavy ion microbeam ; Electron start ; Molecular imaging
• 刊名：Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
• 出版年：2016
• 出版时间：1 August 2016
• 年：2016
• 卷：380
• 期：Complete
• 页码：94-98
• 全文大小：624 K

文摘

A new Time-of-flight MeV Secondary Ion Mass Spectrometry (MeV-SIMS) setup was developed to be used with a capillary microprobe for molecular imaging with heavy primary ions at MeV energies. Due to the low output current of the ion collimating capillary a Time-of-flight (ToF) measurement method with high duty cycle is necessary. Secondary electrons from the sample surface and transmitted ions were studied as start signals. They enable measurements with a continuous primary beam and unpulsed ToF spectrometer. Tests with various primary ion beams and sample types have shown that a secondary electron signal is obtained from 30% to 40% of incident MeV particles. This provides a ToF start signal with considerably better time resolution than the one obtained from transmitted primary ions detected in a radiation hard gas ionization detector. Beam induced secondary electrons therefore allow for MeV-SIMS measurements with reasonable mass resolution at primary ion beam currents in the low fA range.