time-of-flight mass analyzer

Abstract

An electrostatic lens (3), including five cylindrical electrodes (31-35) arrayed along an ion-optical axis (C) and an aperture plate (38) located on a common focal plane of two virtual convex lenses (L1 and L2) formed under an afocal condition, is used as an ion-injecting optical system for sending ions into an orthogonal acceleration unit. The diameter of a restriction aperture (39) formed in the aperture plate (38) determines the angular spread of an exit ion beam. When voltages for making the electrostatic lens (3) function as an afocal system are set, a measurement with high mass-resolving power can be performed at a slight sacrifice of the sensitivity. When voltages for making the lens function as a non-afocal system having the highest ion-passage efficiency are set, a measurement with high sensitivity can be performed at a slight sacrifice of the resolving power. Thus, the operation of an orthogonal acceleration TOFMS can easily be switched between a mode with priority put on the mass-resolving power and a mode with priority put on the measurement sensitivity.

Description

Technical field [0001] The present invention relates to a time-of-flight mass analysis device, and more specifically, to a time-of-flight mass analysis device in an orthogonal acceleration mode (also sometimes referred to as a vertical acceleration mode) that enters ions into an orthogonal acceleration part Ion incident optical system. Background technique [0002] In a time-of-flight mass spectrometer (hereinafter referred to as "TOFMS"), fixed kinetic energy is given to ions derived from sample components to make them fly in a fixed distance space, and the time required for the flight is measured, according to This flight time finds the mass-to-charge ratio of the ion. Therefore, one of the major reasons for the reduction of mass resolution in TOFMS is the deviation of the initial energy of ions. In contrast, in the reflector-type TOFMS, the reflector has the function of correcting the difference in motion energy. A detailed description is omitted, but in a known two-stage r...

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.

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