The Design and Characteristic Features of a New Time-of-Flight Mass Spectrometer with a Spiral Ion Trajectory

Abstract

A new time-of-flight (TOF) mass spectrometer with a corkscrew ion trajectory was designed and constructed. The spiral trajectory was realized by using four toroidal electrostatic sectors. Each had fifteen-stories made of sixteen Matsuda plates piled up inside a cylindrical electrostatic sector. The ions passed the four toroidal electrostatic sectors sequentially and revolved along a figure-eight-shaped orbit on a certain projection plane. During the multiple revolutions, each ion trajectory was shifted by 50 mm per cycle on a direction perpendicular to the projection plane, thus generating a spiral trajectory. The flight path length of one cycle was 1.308 m so that the maximum flight path length became approximately 20 m. The mass resolution, mass accuracy, and ion transmission were tested by utilizing an orthogonally coupled electron ionization source. A mass resolution of 35,000 (FWHM) for m/z greater than 300 was achieved. Even in a lower mass region, mass resolutions of more than 20,000 (FWHM) were confirmed with a doublet of (12)C(5)(1)H(5)(14)N(+) and (13)C(12)C(5)(1)H(6)(+). The mass accuracy was also improved such that it was better than 1 ppm with only one internal standard peak. An ion transmission of approximately of 100% was observed for 15 cycles.