JP2003257361A - High resolution electron energy analyzer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electron energy analyzer capable of dispensing with rotation of an analyzer body and exhibiting enhanced angle resolution and a large drawing angle. <P>SOLUTION: The electron energy analyzer is constituted by a cylindrical electron collecting lens, a conic deflection electrode, and a rotation type position sensitive electron multiplying plate. The conic deflection electrodes are constituted by two pieces of conic deflection electrodes, and an inlet slit and an outlet slit for an electron is opened to the inner conic deflection electrode. The rotation type position sensitive electron multiplying plate is housed in a shield box, and the shield box is rotated around a rotation shaft by rotations of a worm gear. A sample is ionized in a gas cell at a lower part. The emitted electron passes the cylindrical electron collecting lens and a space between two pieces of the conic deflection electrodes. The electron having specified energy is selected, and is detected by the position sensitive electron multiplying plate in the shield box after passing the outlet slit. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to gas phase molecules, surfaces,
The present invention relates to an electron energy analyzer used as one of evaluation methods for solids, clusters, etc., and particularly to an electron energy analyzer having a high angular resolution for gas phase molecules.

[0002]

2. Description of the Related Art In recent years, for the purpose of carrying out precise discussions on electronic states, molecular structures, surface orientations, etc., and for the study of nanotechnology, in addition to analyzing the kinetic energy of emitted electrons, There is an increasing demand for observing the angular distribution of emitted electrons with respect to the traveling direction and the polarization direction of light. Therefore, as typical conventional analyzers, hemispherical analyzers, 127-degree fan analyzers, cylindrical mirror analyzers (CM
A) is present.

The hemispherical type analyzer, which has been used the most, is expected to have double energy convergence and high energy resolution. However, even if an entrance slit is formed in a strip shape to provide angular resolution,
Difficult due to large aberrations. Next, the 127-degree fan-type analyzer has a drawback that it has a converging property only in one direction, it cannot take a wide measurement angle range, and the exit image is curved.

Further, the cylindrical mirror type analyzer (CMA) has a drawback that the information of the angular distribution is lost because the orbits of electrons converge on the central axis. When the above three types of analyzers are used, it is usual to rotate the analyzer body to measure the angular distribution.

Recently, a toroidal type analyzer has been proposed as an analyzer exclusively for measuring angular distribution. It features double convergence and a large take-in angle (about 0.5 sr), and is expected to be a technological innovation in particle measurement. However, since the shape is complicated, there are difficulties in orbit analysis and machining accuracy, and commercially available position-sensitive electron multipliers (multi-anode type, delay line type, CCD
Type, charge distribution type, etc.) It has been put to practical use due to its poor compatibility with other types, and it is only a few examples in Japan and in the world.

[0006]

When such a conventional electron energy analyzer is used to measure the angular distribution of emitted electrons, the analyzer main body is rotated to achieve the angular distribution, so that the angle at which the analyzer is taken in is large. I can't do it, so efficiency is poor,
Since the measurement time is extremely long and the analyzer and the detector are turned, the whole device becomes complicated and large-scale, and the angular resolution is low, the electron capture angle range is small, the rotation mechanism is complicated, and it becomes fragile. There was a problem. Therefore, it is an object of the present invention to realize an electronic energy analyzer that does not require rotation of the analyzer body, facilitates trajectory analysis during design, achieves high machining accuracy, and has high angular resolution and large take-in angle. And

[0007]

In order to solve the above problems, a high resolution electron energy analyzer according to claim 1 of the present invention comprises a cell for ionizing a sample, a cylindrical electron collecting lens, It consisted of a conical deflection electrode and a rotary position-sensitive electron multiplier.

A high resolution electron energy analyzer according to claim 2 of the present invention is a cell for ionizing a sample, a cylindrical electron collecting lens, a conical deflection electrode, and a rotary position-sensitive electron multiplier. In an electron energy analyzer composed of a double plate, the cylindrical electron collection lens is composed of an Einzel lens arranged with a space therebetween, and the conical deflection electrode is composed of two outer and inner electrodes. It is composed of a conical deflection electrode, and an entrance slit and an exit slit are respectively provided in the inner conical deflection electrode so that electrons can pass therethrough, and an electron exit port of the electron collecting lens and the rotary position-sensitive electron multiplier, respectively. It is arranged to face the electron introduction path of the double plate.

Thus, by constructing the energy analyzer with the cylindrical electron collection lens, the novel conical deflection electrode, and the rotary position-sensitive electron multiplier, a high angular resolution and a large acquisition angle can be obtained. It is possible to realize a built-in electron energy analyzer. This analyzer does not require rotation of the main body, and only the position-sensitive electron multiplier plate rotates, which facilitates trajectory analysis during design and has high machining accuracy. Since it has features such as being able to be achieved, the problems of the conventional angle-resolved energy analyzer can be solved.

A high resolution electron energy analyzer according to a third aspect of the present invention comprises a cell for ionizing a sample, and a cylindrical electron collection lens composed of an Einzel lens arranged at a distance. The deflecting electrode is composed of two outer and inner conical deflecting electrodes, and the inner conical deflecting electrode is provided with an entrance slit and an exit slit so that electrons can pass through, and the entrance slit is provided with the electron collecting electrode. The lens was composed of a conical deflection electrode arranged to face the electron emission port of the lens, and a rectangular or oval position-sensitive electron multiplication plate having an electron introduction path covering the entire area of the exit slit.

Thus, by constructing the energy analyzer with the cylindrical electron collection lens, the novel conical deflection electrode, and the rectangular or oval position-sensitive electron multiplying plate,
It is possible to realize an electron energy analyzer with high angular resolution and a large acquisition angle. This analyzer eliminates the need to rotate the position sensitive electron multiplier plate as well as the rotation of the main body, and the angle within the range of 100 degrees. Since the distributions can be measured at the same time, the trajectory analysis at the time of design is easy, and high machining accuracy can be achieved. Therefore, the problems of the conventional angle-resolved energy analyzer can be solved.

A high resolution electron energy analyzer according to a fourth aspect of the present invention is a rotary position-sensitive electron multiplying plate or a rectangular or oval position-sensitive electron multiplying plate according to the second or third aspect. In the case of using a double plate, the entrance slit of the conical deflection electrode is a circular slit or a band-shaped slit opened at a predetermined interval, and the exit slit covers the rotation range of the rotary position-sensitive electron multiplier plate. Alternatively, the configuration is such that it becomes a strip slit formed over the measurement range of the rectangular or oval position-sensitive electron multiplier plate.

A high resolution electron energy analyzer according to claim 5 of the present invention is the high resolution electron energy analyzer according to any one of claims 2 to 4, wherein the conical deflection electrode has an entrance slit and an exit slit. A sector-shaped correction electrode is arranged on the side of the deflection electrode, and correction electrodes are arranged on both ends in the angular direction of the deflection electrode.

The high resolution electron energy analyzer according to claim 6 of the present invention is the high resolution electron energy analyzer according to any one of claims 2 to 5, wherein the electrons of the rotary position-sensitive electron multiplier are An accelerating electron lens is arranged near the introduction path.

Thus, by disposing the correction electrode near the entrance slit and the exit slit of the inner deflection electrode, the disturbance of the electric field due to the "fringe (fringe) effect" near the entrance slit and the exit slit is reduced to 1% or less, Similarly, the four correction electrodes on both ends in the angular direction of the deflection electrode have an effect of preventing disturbance of the electric field at both ends of the deflection electrode. Further, by accelerating the electrons emitted from the exit slit uniformly by using an accelerating electron lens arranged in the electron introduction path to the position-sensitive electron multiplier, an angular resolution of less than 1 degree can be achieved.

[0016]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a top view and a side sectional view of an electron energy analyzer for gas phase molecules, FIG. 2 is a side sectional enlarged view, and FIG. 3 is a top enlarged view. In the figure, 1 is a base, 2,
Reference numeral 6 is two conical deflection electrodes, 3, 4, 7, and 8 are four correction electrodes, 5 is an insulator such as ceramic separating the two conical deflection electrodes 2 and 6, and 9 is a holding member. 10, 11, 12
Is an Einzel lens, 13 is a gas cell, 14 is an entrance slit, and 25 is an exit slit.
Are formed by circular slits or band-shaped slits opened at predetermined intervals.

Reference numeral 15 is a step-like ceramic insulating plate, 16 is an electron introduction path from the exit slit 25, 17 is a rotating arm, 18 is a shield box containing a position-sensitive electron multiplier, and 19 is a shield box. A mounting plate, 20 is a mounting plate for the shield box and a mounting screw for the rotating arm 17, 21 is a swivel shaft, 22 is a shaft holding block with a worm gear, and 23.
Is a base of the worm mechanism, 24 is a pillar of the base 23, 26,
Reference numeral 27 is a correction electrode, and 28 is a worm gear.

As described above, one of the embodiments of the present invention is (a) a cylindrical electron collecting lens, (b) a conical deflection electrode, and (c) a rotary position-sensitive electron multiplier plate. An electron energy analyzer is composed of, and the cylindrical electron collection lens is
Einzel lens 10, which is arranged so as to maintain a distance,
11 and 12, and is provided in front of the entrance slit 14.

The cone-shaped deflection electrode is composed of two cone-shaped deflection electrodes 2 and 6, and a strip-shaped entrance slit 14 is provided so that electrons can pass through the inner cone-shaped deflection electrode 6.
And the exit slit 25 is opened, and the opening angle of these slits is 120 degrees. The correction electrodes 7 and 8 are provided near the entrance slit 14 and the correction electrodes 3 and 4 are provided near the exit slit 25 to form a fan shape of approximately 140 degrees. Further, it has four correction electrodes 26 and 27 on both ends in the angular direction. The correction electrodes 7 and 8 and the deflection electrodes 2 and 6 are screwed to the stepwise ceramic insulating plate 15 so as not to interfere with each other.

The rotary position-sensitive electron multiplying plate is housed in the shield box 18, and the worm gears 28 of the two shaft holding blocks 22 with worm gears are rotated so that the gyration shaft 21 is centered. The rotating arm 17 and the mounting plate 19 of the shield box 18 are rotated to move the shield box 18
Is rotated on a fan shape of approximately 140 degrees composed of the conical deflection electrodes 2 and 6. The rotary arm 17 has a plurality of precision punch holes, and when the electron multiplier plate is rotated to the designated position, the ball plunger screwed to the base 23 of the worm mechanism is fitted into the punch hole, so that the angle Accuracy and repeatability are guaranteed.

At the time of measurement, a sample gas is introduced into the lower gas cell 13 and a beam of light, high-speed electrons, ions or the like is incident to ionize the sample. The emitted electrons are collected by the cylindrical Einzel lenses 10, 11 and 12, and subsequently injected from the entrance slit 14 of the inner conical deflection electrode 6, and between the two conical deflection electrodes 2 and 6. Pass through.

Electrons having a specific energy are selected between the two deflection electrodes 2 and 6, and after exiting the exit slit 25, they are detected by the position-sensitive electron multiplier plate in the shield box 18. The rotary position-sensitive electron multiplication plate rotates the worm gear 28 to rotate the rotating arm 17 and the mounting plate 19 of the shield box 18 about the pivot axis 21 to deflect the shield box 18 into a conical shape. It is rotated on a fan shape of about 140 degrees composed of the electrodes 2 and 6, and the angular distribution is measured over about 100 degrees.

As described above, the position-sensitive electron multiplier plate of this embodiment is large (40 mm in diameter) for detecting electrons, and itself covers a wide angle range of 25 degrees and can be rotated. The angular distribution can be measured over about 100 degrees, and the acquisition angle in this case is 0.14 sr, so that a high angular resolution and a large acquisition angle are realized at the same time.

The potential difference between the two deflection electrodes 2 and 6 must be exactly one-quarter of the electron passing energy. This ratio is derived from the energy dispersion condition of the electron energy analyzer of the present invention, and it has been confirmed from experiments that electrons cannot pass between the deflection electrodes 2 and 6 if deviated from this ratio.

The correction electrodes 7 and 8 arranged near the entrance slit 14 of the inner deflection electrode 6 and the correction electrodes 3 and 4 arranged near the exit slit 25 form a fan shape of about 140 degrees. The correction electrodes 3, 4, 7 and 8 have the effect of reducing the disturbance of the electric field to 1% or less due to the "fringe (fringe) effect" near the entrance and exit slits.

Similarly, the four correction electrodes 26 and 27 on both ends of the deflection electrodes 2 and 6 in the angular direction prevent disturbance of the electric field at both ends of the deflection electrodes 2 and 6. The above correction electrodes are installed in a necessary and sufficient number. The shape of the correction electrode is optimized based on the electron trajectory analysis, and in particular, the optimum value of the brim length of the correction electrodes 7 and 8 arranged near the entrance slit 14 of 7 mm is determined by the central axis (beam of ionized light or the like). It is an important parameter determined by the distance 24 mm from the passage axis) to the entrance slit 14.

FIG. 4 shows a photoelectron spectrum of argon atoms measured by the electron energy analyzer completed by the present invention. Here, a test cone-shaped deflection electrode having circular entrance slits with a diameter of 2 mm opened at intervals of 4.5 to 8 degrees was manufactured, and using this, the angular resolution and the energy resolution were simultaneously examined. The passing energy was set to 1.4 eV. Since the unpolarized helium resonance line is used for ionization, the kinetic energy E _K of the emitted electrons is 5.
It becomes 2 to 5.5 eV, and the electron angle distribution becomes isotropic in the plane perpendicular to the optical axis.

In FIG. 4, the spectrum of argon atoms of the type having slow photoelectrons has a low peak curve, and the spectrum of argon atoms of the type having fast photoelectrons has a high peak curve. From this spectrum and the image data on the position-sensitive electron multiplier, it can be seen that a good energy resolution (ΔE≈0.06 eV) and a high angular resolution (2 degrees or less) are achieved.

As shown in FIG. 4, the energy resolution of this electron energy analyzer was ΔE≈0.06 eV in the case of a circular entrance slit with a diameter of 2 mm, but it was a strip-like entrance slit with a width of 0.5 mm. By replacing with △ E ≒ 0.0
It improved to 12 eV. This is a value comparable to the resolution of a hemispherical energy analyzer.

The electron capture angle is determined by the size of the position-sensitive electron multiplier, and in the case of this prototype, it is about 0.035 s.
r. This electron energy analyzer is
Compared to a high resolution hemispherical energy analyzer, the angular resolution is about 3 times better and the uptake angle is about an order of magnitude better. Furthermore, the exit slit 2 is formed using the accelerating electron lens system 29 shown in FIG.
By accelerating the electrons emitted from 5 uniformly, an angular resolution of less than 1 degree could be achieved (theoretical limit value is 0.3 degree).

As another embodiment of the present invention, instead of the position-sensitive electron multiplying plate of the above-mentioned embodiment, as shown in FIG. 6, 50 × 1 which covers the entire area of the exit slit 25.
If a 50 mm ² rectangular or oval position-sensitive electron multiplier having an effective area equal to or larger than 50 mm ² is used, it is possible to measure the entire angular range without rotating the position-sensitive electron multiplier. As a result, it becomes possible to simultaneously measure the angular distribution in the range of 100 degrees, and a more efficient electron energy analyzer can be manufactured.

When using this rectangular or elliptical position-sensitive electron multiplier having an effective area equal to or larger than that, instead of the accelerating electron accelerating lens 29 shown in FIG. 5, the band-shaped electron shown in FIG. 7 is used. By connecting the accelerating lens 30 after the exit slit 25, an angular resolution of 1 degree is achieved.

[0033]

As described above, the high-resolution electron energy analyzer of the present invention comprises a cylindrical electron collecting lens, a conical deflection electrode, and a rotary position-sensitive electron multiplier or a rectangular or oval shape. By constructing the energy analyzer with the position-sensitive electron multiplying plate, the angular resolution and the taking-in angle are superior to those of the conventional angle-resolved electron energy analyzer, and it is extremely useful for measuring the angular distribution of emitted electrons. Further, it is possible to realize an electron energy analyzer having a high angular resolution and a large acquisition angle comparable to those of a hemispherical energy analyzer having the same energy resolution.

Further, unlike the conventional toroidal analyzer, the high resolution electron energy analyzer of the present invention does not require rotation of the main body, and the shape and arrangement of the deflection electrode and the correction electrode of the device of the present invention are electron orbit analysis. Can be easily determined based on the above, and high-precision cutting is possible.

[Brief description of drawings]

FIG. 1 is a top view and a side sectional view of an electron energy analyzer of the present invention.

FIG. 2 is an enlarged side sectional view of an electron energy analyzer of the present invention.

FIG. 3 is an enlarged top view of the electron energy analyzer of the present invention.

FIG. 4 is a photoelectron spectrum diagram of Ar atoms by the device of the present invention.

FIG. 5 shows another embodiment of the electron energy analyzer of the present invention.

FIG. 6 is a diagram of another embodiment of the electron energy analyzer of the present invention.

FIG. 7 is a top view of another electron acceleration lens of the present invention.

[Explanation of symbols]

1 Base 2, 6 Conical Deflection Electrode 3, 4, 7, 8 Correction Electrode 5 Insulator 9 Holding Member 10, 11, 12 Einzel Lens 13 Gas Cell 14 Entrance Slit 15 Stepped Ceramic Insulation Plate 16 Electron Introduction Path 17 Rotating arm 18 Shield box containing position-sensitive electron multiplication plate 19 Shield box mounting plate 20 Mounting screw 21 Revolving mandrel 22 Shaft holding block with worm gear 23 Worm mechanism base 24 Base stanchion 25 Exit Slits 26, 27 Correction electrode 28 Worm gear 29, 30 Electron acceleration lens

Claims (6)

[Claims] 1. A high-resolution electron comprising a cell for ionizing a sample, a cylindrical electron collecting lens, a conical deflection electrode, and a rotary position-sensitive electron multiplying plate. Energy analyzer. 2. The cylindrical electron collection lens is composed of an Einzel lens which is arranged with a space therebetween, and the conical deflection electrode is composed of two outer and inner conical deflection electrodes. An entrance slit and an exit slit are provided in the inner conical deflection electrode so that electrons can pass through the electron exit port of the electron collection lens and the electron introduction path of the rotary position-sensitive electron multiplier plate, respectively. The high resolution electron energy analyzer according to claim 1, wherein the high resolution electron energy analyzers are arranged to face each other. 3. A cell for ionizing a sample, a cylindrical electron collection lens composed of an Einzel lens arranged at a distance, and an outer and inner conical deflection with two deflection electrodes. The inner conical deflection electrode is provided with an entrance slit and an exit slit so that electrons can pass therethrough, and the entrance slit is a conical shape arranged to face the electron exit port of the electron collection lens. And a rectangular or oval position-sensitive electron multiplying plate having an electron introduction path that covers the entire area of the exit slit, and a high resolution electron energy analyzer. 4. The entrance slit of the conical deflection electrode is a circular slit or a band-shaped slit opened at a predetermined interval, and the exit slit is over the rotation range of the rotary position-sensitive electron multiplier plate, or The high resolution electron energy analyzer according to claim 2 or 3, wherein the high resolution electron energy analyzer is a band-shaped slit formed over a measurement range of the rectangular or oval position-sensitive electron multiplier plate. 5. A fan-shaped correction electrode is arranged near the entrance slit and the exit slit of the conical deflection electrode, and correction electrodes are arranged on both ends in the angular direction of the deflection electrode. The high resolution electron energy analyzer according to claim 2. 6. The high resolution electron energy analyzer according to claim 2, wherein an accelerating electron lens is arranged in the vicinity of an electron introduction path of the rotary position-sensitive electron multiplier. .