Evaluation of multi-turn time-of-flight mass spectrum of laser ionization mass nanoscope

We have evaluated the performance of a multi-turn time-of-flight mass spectrometer (MULTUM II) equipped with the ion injection optics of a laser ionization mass nanoscope (LIMAS). We surveyed the optimal parameters for the ion injection optics, which consist of ion extraction from a sample surface and ion introduction into MULTUM II. We developed mass calibration methods for correcting the modulation of load voltage for MULTUM II and injection timing for the ion injection optics. As a result, the mass-resolving power of LIMAS increased linearly with increasing the flight path length, and reached 6.2 × 10⁵ (full width at half maximum) at 1000 multi-turn cycles of MULTUM II (flight path length: 1.3 km). The transmittance of LIMAS decreased to 60–70% after 20 multi-turn cycles of MULTUM II, compared with the linear mode transmittance. The transmittance per multi-turn cycle became constant (99.96%) after 20 multi-turn cycles. A useful yield of 3 × 10⁻³ for Si ions was obtained for LIMAS at 30 multi-turn cycles of MULTUM II.