JP2000268770A - Ion guide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to neglect curvature accuracy of each rod by bending the bent cut-in part of the rod. SOLUTION: A rod 13 is bent degleg to thereby discharge neutron particles having no electric charge from the inside to the outside of an ion guide. To bent the ion guide 13, a deep cut-in portion 14 is formed at only one part of the rod 13, and then the guide is bent by using it. Four rods 13 bent at their cut-in portions 14 are screwed toward the outside of the guide 13 by the use of four holders 15 and fixed integrally with each other. When fixing, bent portions can be moved freely to some extent so that they 13 can be assembled in the form of a doglegged Q pole. The cut-in portions 14 are irected toward the outside of the guides 13 so that no distortion of high frequency electric field is given to the side of ion passage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion guide, and more particularly, to an ion guide capable of preventing neutral particles unnecessary for mass spectrometry from entering a mass spectrometry system.

[0002]

2. Description of the Related Art A method of introducing ions generated under atmospheric pressure into a high vacuum region using an ion guide is widely known as one technique of mass spectrometry. FIG. 1 shows a configuration of a conventional ion guide. In the figure, reference numeral 1 denotes a differential exhaust chamber surrounded by two orifices 2 and 3,
It is evacuated to about several Torr by a rotary pump (RP) 4.

A first intermediate chamber 5 is evacuated to a low vacuum of about 10 ⁻² Torr by a diffusion pump (DP) 6.
Reference numeral 7 denotes a second intermediate chamber that is evacuated to a medium vacuum of about 10 ⁻⁵ Torr by the DP 8, and 9 denotes an analysis unit that is evacuated to a high vacuum of about 10 ⁻⁷ Torr by the DP 10. Curved 4
The Q-pole ion guide 11 composed of two rods is installed so as to bridge from the vicinity of the orifice 3 to the vicinity of the entrance of the analyzer 9.
A high-frequency voltage from a high-frequency power supply 12 is applied to the opposing rods in the same phase as shown in the AA cross-sectional view.

Incidentally, the Q-pole ion guide shown in FIG. 1 employs two vertically overlapping rods of four rods constituting the Q-pole ion guide for the purpose of simplifying the drawing. The illustration is omitted, and only two lines arranged in the horizontal direction are represented.

The ions introduced into the differential exhaust chamber 1 from the orifice 2 reach the inlet of the Q-pole ion guide 11 through the orifice 3 and vibrate by an electromagnetic field generated in the ion guide by a high-frequency voltage. While being analyzed, via the first intermediate chamber 5 and the second intermediate chamber 7,
Is transported in the curved Q-pole ion guide 11 to the entrance of the ion beam.

At this time, neutral particles unnecessary for mass spectrometry do not respond at all to fluctuations in the high-frequency electromagnetic field generated in the ion guide. Being eliminated towards
It cannot reach the entrance of the analysis unit 9. In this way, the Q-pole ion guide 11 is curved gently as shown in the figure to prevent neutral particles from entering the analyzer 9 and reduce the contamination of the analyzer 9.

[0007]

However, in such a configuration, the Q-pole ion guide 11 is usually a combination of four rods, and it is difficult to keep the bending accuracy of each rod the same. Was. Also,
When assembling the Q-pole ion guide 11 while keeping the gap between the rods constant, the assembling method is difficult and there is a problem that the gap accuracy between the rods cannot be maintained.

In view of the above, an object of the present invention is to eliminate the need to worry about the bending accuracy of each rod of the ion guide.
In addition, an object of the present invention is to provide an ion guide that can be assembled while maintaining a gap between rods at a predetermined value.

[0009]

In order to achieve this object, an ion guide according to the present invention is bent by arranging at least four even-numbered bent rods around an ion passage. An ion guide having an ion passage formed therein, wherein a bent portion of each rod is bent at a cut portion provided in the rod.

Further, each of the rods is integrally fixed by a holder at a straight portion of each rod.

Further, the holder is made of an insulating material.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows an embodiment of a Q-pole ion guide according to the present invention. In the figure, (a) is the original form of the rod constituting the Q-pole ion guide, (b) is the overall configuration when the Q-pole ion guide is assembled using the rod, and (c) is the Q-pole ion guide. 2 shows a cross-sectional view of the vicinity of the holder.

[0013] Of these, FIG. 2B shows two rods constituting the Q-pole ion guide, which are vertically stacked, are omitted, and the remaining two rods are omitted. It is depicted as a cross section cut through a plane containing the book rods.

As is clear from FIGS. 2 (a) and 2 (b), in the present embodiment, the neutral particles having no charge are ionized by bending the rod in a polygonal line instead of bending it gently. Eliminate the guide from inside to outside. The method of bending the ion guide is shown in FIG.
As shown in (1), a deep cut 14 is made in each rod 13 of the Q pole, and the rod 13 is bent using the cut. The AA cross-sectional view shows a cross section of the rod of the cut portion 14.

As shown in FIG. 2B, the four rods 13 bent at the cuts 14
Is screwed to the outside of the ion guide using four holders 15 made of an insulator, for example, an insulator, and is integrally fixed. Since the bent portion can be freely moved to some extent during fixing, it is possible to assemble the shape of the bent linear Q pole very easily.

In this case, the cut portion 14 of the rod 13 is directed to the outside of the ion guide, but this is for preventing distortion of the high-frequency electric field on the ion passage side of the ion guide. However, even if the notch 14 of the rod 13 is assembled with the ion guide facing the inside of the ion guide, the distortion generated in the high-frequency electric field in the ion guide is small, and the practical adverse effect is small.

FIG. 2C is a sectional view taken along the line BB of the Q-pole ion guide cut at the holder 15. As is clear from the figure, the four rods 13 are arranged opposite to each other while maintaining an equal interval, and are fitted into a concave portion 16 carved inside the annular holder 15, and set screws 17.
It is fixed by screwing and assembled. Since the assembling accuracy is reproducible, even when the Q-pole ion guide is disassembled for cleaning, the Q-pole ion guide can always be reassembled as before, and the predetermined performance as the ion guide can be easily obtained.

Although the present embodiment is directed to a Q-pole (four) ion guide, the present invention is not necessarily limited to a Q-pole, and the hexapole (six) can be used.
It can also be applied to an ion guide of octapole or (8).

Further, in the present embodiment, the ion guide in which a notch is formed in one portion of the rod to be bent in a broken line shape is shown, but the notch of the rod is not limited to only one position. As shown in FIG. 3, the rod may be of a type in which notches are formed in two places and two places are bent, or a type in which three or more places are bent, not shown. May be.

In this embodiment, the conditions are set such that one set of rods is fixed using four holders made of insulating material. However, as shown in FIG. It is also possible to reduce the number of holders used.

[0021]

As described above, according to the ion guide of the present invention, a cut is made in a portion corresponding to the bending position of the rod of the ion guide, only this portion is bent with a certain degree of accuracy, and this bent portion is formed. Since a plurality of rods are collected and integrally fixed with a holder made of an insulator, a gap between the rods is assembled with high accuracy, and the quality as an ion guide can be easily maintained.

Further, even when the rod is disassembled for cleaning the ion guide, the rod assembly accuracy is reproducible, so that the rod can always be reassembled as before, and the predetermined performance as the ion guide can be easily achieved. Can be put out.

[Brief description of the drawings]

FIG. 1 is a diagram showing a conventional ion guide.

FIG. 2 is a diagram showing one embodiment of an ion guide according to the present invention.

FIG. 3 is a diagram showing one embodiment of an ion guide according to the present invention.

FIG. 4 is a view showing one embodiment of an ion guide according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Differential exhaust chamber, 2 ... Orifice, 3 ... Orifice, 4 ... Rotary pump, 5 ... 1st intermediate chamber, 6 ...
Diffusion pump, 7 ... second intermediate chamber, 8 ... diffusion pump, 9 ...
・ Analyzer, 10 ・ ・ ・ Diffusion pump, 11 ・ ・ ・ Q pole ion guide, 12 ・ ・ ・ High frequency power supply, 13 ・ ・ ・ Rod, 14 ・ ・ ・
Notch, 15 ... holder, 16 ... recess, 17 ... set screw.

Claims (3)

[Claims] 1. By disposing four or more even-numbered bent rods around an ion passage,
An ion guide having a bent ion path,
The bent portion of each rod is bent at a cut portion provided in the rod. 2. The ion guide according to claim 1, wherein each rod is integrally fixed by a holder at a linear portion of each rod. 3. The ion guide according to claim 2, wherein said holder is made of an insulating material.