Time-of-flight mass spectrometer

Abstract

An electrostatic lens (3), in which, as an ion incident optical system for sending ions into an orthogonal acceleration unit, five cylindrical electrodes (31-35) are arranged along an ion optical axis (C), and an aperture plate (38) is disposed on a common focal plane of two virtual convex lenses (L1, L2) formed under an afocal condition, is used. The diameter of an aperture opening (39) formed in the aperture plate (38) determines the angular spread of the exiting ion beam. When an applied voltage is set such that the electrostatic lens (3) becomes an afocal system, measurement with a high mass resolution can be performed though the sensitivity is sacrificed slightly, and when an applied voltage is set such that the electrostatic lens (3) becomes a non-afocal system in which an ion passing rate is maximized, measurement with a high sensitivity can be performed though the resolution is sacrificed slightly. Thus, in an orthogonal acceleration-type TOFMS, a mass-resolution priority mode and a measurement sensitivity priority mode can be switched readily.

Description

technical field [0001] The present invention relates to a time-of-flight mass spectrometer, and more specifically, to a method for injecting ions into an orthogonal acceleration section in a time-of-flight mass spectrometer of an orthogonal acceleration method (also sometimes referred to as a vertical acceleration method). Ion incidence optics. Background technique [0002] In a time-of-flight mass spectrometer (hereinafter abbreviated as "TOFMS"), ions derived from sample components are given fixed kinetic energy to fly in a fixed distance space, and the time required for the flight is measured. According to The mass-to-charge ratio of ions is obtained from this time-of-flight. Therefore, one of the major causes of reduction in mass resolution in TOFMS is the variation in initial energy possessed by ions. On the other hand, in the reflector-type TOFMS, the reflector has the function of correcting the difference in motion energy. A detailed description is omitted, but in ...

AI Technical Summary

Problems solved by technology

[0010] In addition, in the above-mentioned conventional structure, the mass resolution is determined by the gap between the two slit plates and the width of the slit opening. Therefore, for example, it is desirable to perform high-sensitivity measurement even if the mass resolution is slightly lowered. Requirements, mechanical operations such as replacing the slit plate of the beam limiting mechanism with a slit plate with a different slit opening width or adjusting the gap between the slit plates

Such an operation is cumbersome and labor-intensive

In addition, there is also a problem in the reliability of the mechanism that can perform such mechanical adjustment and replacement.

Images