Construction of a shuttered time-of-flight mass spectrometer for selective ion detection

Abstract

By placing a pulsed, high-voltage steering plate between the ion source and detector in a time-of-flight mass spectrometer, the signal-to-noise ratio of the mass of interest is improved by more than an order of magnitude. This improvement arises from (1) suppression of ions of other masses formed at the same time as the ion of interest and (2) suppression of ions formed at different times and different locations whose arrival time at the detector is nearly coincident with the mass of interest. The advantages of this simple device are demonstrated in the detection of molecular hydrogen in the presence of other species.