Time-of-flight mass spectrometer

Abstract

A novel, time-of-flight mass spectrometer for the qualitative and quantitative analysis of elemental, molecular, and isotopic chemical samples is provided which offers increased sensitivity, speed of analysis, resolving power, and signal-to-noise ratios than prior mass spectrometers by properly sampling and collimating an ion beam from a continuous ion source, decelerating said ion, forming ion packets from the continuous ion beam, storing said ion packets, extracting and accelerating the ion packets along a stable flight path, transversely compressing said packets, focusing ions of similar mass, and detecting the focused ion masses. The mass spectrometer includes an ion optics assembly and an analyzer disposed along a common axis coincident with a continuous beam of sampled ions. The relationship between the ion extractor and accelerator are such that ions of isomass are focused at at least one point in space in the analyzer along a narrow flight path so as to be either removed from the flight path or allowed to proceed and be detected at substantially the same time. The separate modulation and extraction steps, when coupled with the space-focusing and selected deflection of certain ionic species, results in higher sensitivity, greater analysis speed, higher resolving power, and improved signal-to-noise ratio than achieved in prior orthogonal or on-axis time-of-flight mass spectrometers. A novel method achieved by the apparatus is also disclosed.