JPH02270256A - Simultaneous detection type pass analyzing device - Google Patents

Abstract

PURPOSE:To employ a detector which is greatly subject to a magnetic field without decreasing gain by arranging a 4-pole electrostatic lens on an ion path between a sector electric field and a uniform magnetic field to give the expanded image face of ions clearance from the projected edge of the magnetic field. CONSTITUTION:A 4-pole electrostatic lens 5 is arranged between an electric field 2 and a magnetic field 3 so that the 4-pole electrostatic lens 5 can provide divergent action on a track face and convergent action on a normal direction thereto. The expanded image face of ions can be given clearance from the projected edge of the magnetic field, accordingly. It is thus possible to detect ions while keeping adverse effect such as decreased gain to a minimum if a two-dimensional ion detector 4 which is subject to the magnetic field such as a channel plate is used.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a simultaneous detection type mass spectrometer such as a MattauCh-11erZOg type mass spectrometer, and in particular, to a simultaneous detection type mass spectrometer such as a MattauCh-11erZOg type mass spectrometer, and in particular an electric detection type detector such as a channel plate as an ion detector. The present invention relates to a simultaneous detection type mass spectrometer suitable for use.

[Prior Art] Mass spectrometers are broadly classified into sweep types that obtain mass spectra by magnetic field sweeping and the like, and simultaneous detection types that record mass spectra on, for example, a photographic plate without performing sweeps. The simultaneous detection type, which detects all ions at the same time, makes better use of ions compared to the sweep type, which has a lower efficiency in using ions generated by the ion source because it discards all ions with masses different from those entering the detector. It has high efficiency and, in principle, high sensitivity. However, the sensitivity of photographic plates, which are conventionally used mainly as detectors in simultaneous detection types, is extremely low compared to the secondary electron multiplier tubes used in sweep types, and it is difficult to achieve higher sensitivity than sweep types. was difficult.

Incidentally, recently, a highly sensitive two-dimensional ion detector using a channel plate that can detect the position and intensity of incoming ions over a large area has been developed. If this is placed on the spectrum imaging plane of a simultaneous detection mass spectrometer and a wide range of mass spectra can be detected simultaneously,
It is possible to dramatically increase sensitivity. - On the other hand, in order to obtain high resolution over a wide mass range, double convergence must be established at all positions on the spectral imaging plane. In a sweep-type double-focusing mass spectrometer, the direction convergence surface and the energy convergence surface do not perfectly match.
Since they intersect, double convergence only holds true at one point and not at other positions.

A Mattauch-11 crzog type mass spectrometer as shown in FIG. 4 is an apparatus designed so that the direction convergence surface and the energy convergence surface completely overlap in the same straight line. In Fig. 4, 1 is an ion source, 2 is a fan-shaped electric field, and 3
is a uniform fan-shaped magnetic field, and 4 is a two-dimensional ion detector such as a photographic plate.

In this mass spectrometer, as a direction focusing condition, the ion source 1 is placed at the focal point of the fan-shaped electric field 2, and the ion beam between the electric field and the magnetic field is made parallel. Then, since the energy convergence condition is obtained by adjusting the ratio of the deflection angles φe and φm of the electric field and the magnetic field, double convergence is established regardless of the radius of the magnetic field orbit of the ion. The double converging surface (imaging surface) is on a straight line passing through the ion incidence surface into the magnetic field, and if the photographic plate 4 is placed on this surface, a clear image can be obtained for all masses (orbit radii). A mass spectrum is obtained.

There were two types of devices proposed by Mr. Mattauch and Mr. Llerzog as shown in the table below.

Table 1 (a) (b) ε10° 19.470 φm 90° 109.47゜φe 31.8° 63.65' L, 0.707r, O L, 00 In Table 1, ε1 is the ion beam to the magnetic field. angle of incidence,
Ll is the distance between the ion source source slit and the electric field, r is the radius of the ion center orbit in the electric field, and L3 is the distance between the magnetic field end face and the spectrum imaging plane.

Of these, the device (a) was actually manufactured and is generally used by Matt
The term auch-11erzog mass spectrometer refers to this optical system.

In the device shown in (b), φ is made as large as possible in order to make the angle at which the ion beam enters the dry plate as close to a right angle as possible (it was believed that this would make the spectral lines clearer). The corner is 5" compared to 45" in (a)
It has increased to 4.73”.

[Problems to be Solved by the Invention] In the Mattauch-Herzog mass spectrometer described above, as can be seen from the conditions L and -0, the spectral imaging plane is formed at the magnetic field output end face. The magnetic field intensity at the magnetic field output end face is extremely large, and there is no problem when using a photographic plate as a detector, which is not affected by the magnetic field, but when using a channel plate, which is significantly affected by the magnetic field, the gain will be significantly reduced. This causes a serious problem in practical use.

The present invention has been made in view of the above-mentioned points, and by separating the spectral imaging plane from the magnetic field emission end face to the free space side and making it possible to arrange the two-dimensional ion detector at a position where the magnetic field strength is small. The purpose of this research is to realize a simultaneous detection mass spectrometer that can employ a detector that is significantly affected by magnetic fields, such as a channel plate, without loss of gain.

[Means for Solving the Problems] In order to achieve this object, the simultaneous detection mass spectrometer of the present invention includes an ion source, a fan-shaped electric field into which analyte ions generated from the ion source are incident, and a fan-shaped electric field. A simultaneous system that combines a uniform magnetic field in which ions that have passed through the ion beam are incident and the ions are expanded according to their mass-to-charge ratio, and a two-dimensional ion detector that is placed along the imaging plane where the ions are expanded by the uniform magnetic field. The detection type mass spectrometer is characterized in that an electrostatic quadrupole lens is placed on the ion path between the fan-shaped electric field and the uniform magnetic field, so that the ion development imaging plane is separated from the magnetic field output end face. .

C Effect In the present invention, an electrostatic quadrupole lens is placed between an electric field and a magnetic field, and this electrostatic quadrupole lens has a diverging effect on the orbital plane and a converging effect in a direction perpendicular to it. As a result, the ion development imaging plane can be separated from the magnetic field output end face, and convergence in the vertical direction is also improved.

[Example code] Hereinafter, the present invention will be explained in detail based on the drawings.

The above (
a).

The optical system in (b) was calculated ignoring the influence of edge groups, and when this influence is taken into account, some modifications must be made depending on the gap between the magnetic field and electric field. In this way, the numerical values and -order of the ion optical system parameters are corrected in consideration of the influence of edge groups.

The quadratic coefficients are shown in Table 2A and Table 2B.

(Margin below) Table 2 A (a) (b) (c) φ,
31.49' ← ←φ
90", 4-r, 1.0 ←
←r s 1.0 0
．． 5 0.25ε1 06
← ←ε2 −45°
, .

L, 0.758 −
-L, O40← ←L
i -0,005-0,009-0,018
A x -0,956-0,478-0,2
39A, 0.5 0.25
0.125A, 1. (1281,
0421015A s 3.231
2.438 1.989A,,
1,178 -0.232 -1.75
7A,, 2.485 1.977
2.192Aaa -0,287
-0,287-0J54A□ -1,242-3
,036-8,786A,s-7,847
-14,418-34,878Aas -12,
35 (7,092-34,586G, 1.
03 1.07 1.13Gs
3.25 2.52 2.
23A, /Ax 0.523 Table 2B (a) (b) (c)φ,
58.7' ← ←
φ, 109.47” ←
←re 1.0
← ←r = 1.0
0.5 0.25εo 1
9.47 @ Th.

ε2 −85.27 ” ←
0L + 0.135
← ←L20.32 ←
←L ) -0,002-0,0
05-0,009Ax -1,304-0,6
52-0,328A, 0.887
G, 333 0.167A, 0J77
0.429G, 526As
2.450 1.584 1.212A
,, 0.618 -0.132
-0.948A, a 1.945 2.
021 2.828Aa--1,235-1,1
98-1', 514A, -0,170-0
, 420-1, 316A, s-IJ51
-2J87 -5.708A□ -4,8
03-4, 214-8, 48JIG, 1.0
1.0 1. OGs 2
．． 46 1.5g 1.45Af/A
x O,512 In Table 2, r is the radius of the central orbit of the ion in the magnetic field, Ax is the image magnification, A is the mass dispersion coefficient, A,, A is the spread of the beam in the y direction perpendicular to the orbital plane. A coefficient indicating
ll#+ A mar A mar A FFI A
FjrA□ is the second-order aberration coefficient, and G, , G is the value of the maximum coefficient within the magnetic pole gap. The larger A is, the better; however, the closer the other coefficients are to zero, the better. When G is small, the beam size in the direction perpendicular to the orbital plane becomes small, and the transmittance of the ion beam passing through the magnetic pole gap improves.

All trajectory calculations in this specification were performed using a computer program published in the journal "Mass Spectrometry." Also, the electric field electrode gap and the magnetic pole gap are each 0.08 r e
, 0.04 r *.

In the optical system in Table 1 (a), a positive incident angle (19,47°) is applied to the magnetic field in order to move the spectral imaging position to a position with a deflection angle larger than φ, -90°. He gave it. In this case, leaving the incident angle unchanged, φ,
If we set the magnetic field boundary so that it is -90" (see Figure 4), the ion beam has not yet converged at the magnetic field exit, so the spectrum imaging plane will move away from the magnetic field edge and extend into free space. Become.

According to Mattauch and Herzog's calculations, Table 1
In the case of (b), the maximum value φ that satisfies the double convergence condition when εr -19,47@, -63,85', φl1l
At -109.47°, it became Ll-〇, and it was not possible to increase ε1 any further.

However, considering the influence of edge groups, ε1−19.47
', φ, corresponding to -109.47°, is
56.7'' as shown in Table 2B, and Ll at that time is 0°135. Therefore, in order to make Ll (distance from the magnetic field emission surface to the spectral imaging surface) as long as possible, the value of E is can be made larger than the 19.47° set by Mattauch and Oerzog.

Table 3 shows the results of calculations based on this idea.

(Margin below) Table 3 (a) (b) (c) φ, 63a ← ← φ, 90° ← ← r* 1.0 ← ← r, 1.0 0.5 0.25 ε, 23. 73 ← ← ε2-45° ← ← L, 0.023 ← ← L, 0.32 ← ← La O, 3010, 144-0,058Ax -0
,980-0,490-0,245A, 0.5 0
．． 25 0.125A, 0.3540.438 0
．． 595Aa 2.8961.827 1.433A
,, 0.13010.226-0.09OA, 40.
82G 0.673 0.869Aaa -0,877
-0,528-0,593A, -0,233-0,
581-1,837A□-1,591-2,924-7
,391A□-3,728-4,139-7,608G
, 1.0 1.0 1.0 Gs 2.09 1.44 1.44A, /Ax 0
．． 510 As can be seen from Table 3, ε+ ""23.73 ',
φ.

-63''. The optical system shown in FIG. 4 is based on the dimensions shown in Table 3.

The inventor further developed this idea by inserting a Q lens between the electric field and the magnetic field, which further increased ε1, further lengthened L, and moved the spectral imaging plane further away from the magnetic field end face. It has been found that it is possible to arrange the lens at a certain position, and at the same time, it is possible to improve the convergence in the vertical direction and to enhance the effect of so-called three-dimensional convergence.

FIG. 1 is an ion optical diagram showing an embodiment of the present invention.

The difference from FIG. 4 is that an electrostatic quadrupole lens 5 is disposed between the fan-shaped electric field 2 and the uniform magnetic field 3. FIG. 2 is a diagram showing a cross-sectional structure of this electrostatic quadrupole lens and an example of the configuration of an electric circuit for applying a potential to it. The electrostatic quadrupole lens 5 is composed of four cylindrical electrodes arranged at 90° intervals around the ion path, as shown in FIG. A positive potential is applied to opposing electrodes in the direction perpendicular to the orbital plane (X direction), and the radial direction (X direction) of the ion beam is
A negative potential is applied to electrodes facing each other. However, this applies only when the ions to be handled are positive ions; in the case of negative ions, the polarity is reversed.

By applying such a potential, the quadrupole lens 5 is given a converging action in the X direction and a diverging action in the X direction.

Furthermore, if the ion beam incident on the magnetic field after passing through the quadrupole lens 5 is made to be a parallel beam, the double convergence condition is independent of r, φ1. φ,.

Since it is determined by ε1, the double convergence surface, that is, the spectral imaging surface becomes a straight line passing through the magnetic field incidence surface. In this way, in order to make the ion beam parallel after passing through the quadrupole lens, it is sufficient to adjust the strength and length of the lens.

Based on the above considerations, Table 4 shows an example of an ion optical system designed with consideration given to reducing the second-order aberration coefficient.

Table 4 (a) (b) (c) φ, 70° ← ← φ, 90° ← r, 1.0 ← ← r,,, 1.0 0.5 0.25ε, 38.1
1 ← ← ε2-45' ← ← QLO,12← ← QK -1,5← ← L, 0.031 ← ← L210.05 ← ← L2□0.15 ← ← L] 0.4350.211 0.0 92A , -0
,831-0,415-0,208A, 0.5 0
．． 25 0.125A, -1,221-0,703-
0.177A, 0.9B40.354 0.44O
A□0.9290.794 0.956A, a -0J
15-1.006-1.89OA, 0.0820.
588 1.159A, -0,298-0,282
-0,463A,, 0.384-0.281-1.6
75A□-0,379-0,737-2,211G,
0.94 0.94 0.94G, 1.50 1
．． 50 1.5OA, /Ax O, 602 In Table 4, L21 is the distance between the electric field output end and the quadrupole lens input end, L2□ is the distance between the quadrupole lens output end and the magnetic field input end, and QL is the quadrupole lens The length of and QK indicate the strength of the quadrupole lens, respectively. Note that Qx is normalized by the ion acceleration voltage.

Comparing this Table 4 with the case of Table 3, it can be seen that L is larger and the spectrum imaging plane is further away from the magnetic field end face. Also, many of A and %G are smaller, and it can be seen that the characteristics are improved in all respects.

FIG. 3 is an ion optical diagram showing another embodiment of the present invention. In this embodiment, an electrostatic quadrupole lens 6 is also inserted between the ion source 1 and the electric field 2. Table 5 shows an example of an ion optical system with such an arrangement.

(Margin below) Table 5 (a) (b) (c) φ, 58' ← ← φ, 90° ← ← r* 1.0 ← ← r, 1.0 0.5 0.25 ε, 35 − − ε2−45° ← ← Qt O,12← ← To Q, −1,5← ← 2−1.5 to Q ← ← L++ 0.089 ← ← L1□0.05 ← ← L2+ 0.05 ← ← L2□0.15 ← ← L3 0.4070.197 0.085Ax-0,7
87-0,393-0,197A, 0.5G,
25 0.125A″, -1°367-0.690-0
．． 211A, 1.182G, 591 0.81O
A,, 1.08B 0.811 0.834A,a
0J32-0.311-0.901A, -0,14
60,1410,397Ayy -0,415-0,2
41-0,17BA□0.671-0.182-0.8
77A□-0,586-0,965-2,608G,
0.72 G, 58 0.57 Gs 1.48
1.4B 1.46A=/Ax 0.835 In Table 5, Lll is the distance between the source slit and the input end of the quadrupole lens 6, LI□ is the distance between the output end of the quadrupole lens 6 and the electric field input end, Q Kll Q K2 indicates the strength of the quadrupole lens 6.5, respectively.

As can be seen by comparing Table 5 with Table 4, A,,A,,A,,,A□,A1゜G,,G,representing the convergence in the y direction.
Many of the coefficients are improved in Table 5, and this is especially noticeable as the radius of rotation of the magnetic field becomes smaller. From the above, it can be determined that the three-dimensional convergence is further improved by adding a quadrupole lens to the entrance side of the electric field.

Furthermore, by adding a quadrupole lens on the entrance side of the electric field, Ax becomes smaller, so that for the same resolution, the width of the source slit can be increased, and sensitivity can be improved.

Furthermore, by using two quadrupole lenses as in this embodiment, the quadrupole lens 6 performs energy convergence, the quadrupole lens 5 performs directional convergence, and both energy convergence and directional convergence can be electrically adjusted independently. This is extremely advantageous in practice.

[Effect] As detailed above, according to the present invention, by arranging the quadrupole lens between the electric field and the magnetic field, the spectrum imaging plane can be separated largely from the magnetic field end face, so that the magnetic field such as the channel plate Even if a two-dimensional ion detector is used, which is susceptible to the effects of

In addition, by placing a quadrupole lens between the ion source and the electric field, the 3D focusing performance is further improved, and the mass spectrometer can electrically adjust energy focusing and directional focusing independently. Realized.

[Brief explanation of drawings]

1 and 3 are ion optical diagrams showing one embodiment of the present invention, FIG. 2 is a diagram showing a cross section of an electrostatic quadrupole lens and an example of an electric circuit for applying a potential to it, and FIG.
The figure is a diagram for explaining a Mattauch-Herzog type mass spectrometer. 1: Ion source 2: Fan-shaped electric field 3 Knee-like magnetic field 4: Two-dimensional ion detector 5.6 = Electrostatic quadrupole lens

Claims (2)

[Claims] (1) An ion source, a fan-shaped electric field into which analyte ions generated from the ion source are incident, and a uniform magnetic field into which ions that have passed through the fan-shaped electric field are incident and expand the ions according to their mass-to-charge ratio; In a simultaneous detection mass spectrometer equipped with a two-dimensional ion detector arranged along an imaging plane where ions are developed by a uniform magnetic field, an electrostatic A simultaneous detection mass spectrometer characterized in that the ion development imaging plane is separated from the magnetic field output end face by arranging a polar lens. (2) The simultaneous detection type mass spectrometer according to claim 1, characterized in that an electrostatic quadrupole lens is disposed on an ion path between the electric field and the ion source.