Mass spectrometer and method of determining mass-to-charge ratio of ion

Abstract

The present invention provides a time of flight mass spectrometer having a spiral flight path, whose mass resolution can be appropriately changed with respect to the analysis object or other factor without any complicated alteration or addition of the mechanical construction. In a specific form of the invention, the mass spectrometer includes deflecting electrodeslocated between semi-cylindrical electrodesandfor making ions fly along a spiral path. The deflecting electrodesgenerate deflecting electric fields for shifting the ions in the axial direction of the semi-cylindrical electrodesand. The voltage applied to the deflecting electrodesis changed according to the mass resolution required. The deflecting electric fields are generated or removed with the change of the voltage, which makes the ions fly either along a spiral path or in the same loop orbit. The flight distance of the ions can be controlled as desired by regulating the voltage so that the ions fly in the loop orbit an appropriate number of times. Thus, the mass resolution can be arbitrarily controlled.