Channel electron multiplier and ultraviolet electron spectrum analyzer

Abstract

The invention provides a channel electron multiplier and an ultraviolet electron spectrum analyzer, and relates to the field of electron yield detection. The channel electron multiplier comprises a channel electron multiplier body and a first focusing electrode connected to the inlet position of the channel electron multiplier body. The first focusing electrode is in a hollow ring shape, the outer edge size is larger than the inlet size of the channel electron multiplier body, and the voltage is smaller than or equal to the input voltage of the channel electron multiplier body. The first focusing electrode is directly arranged at the inlet of the channel electron multiplier body, and emergent electrons of a measurement sample directly enter the inlet of the channel electron multiplier body after being attracted and gathered by the first focusing electrode, so that loss of the electrons is avoided; meanwhile, the outer diameter size of the first focusing electrode is larger than the inlet size of the channel electron multiplier body, the electron attraction range of the channel electron multiplier body is enlarged, and the electron collection efficiency is improved. On the basis, the detection capability of the ultraviolet electron spectrum analyzer is also improved.

Description

Technical Field

[0001] The invention relates to the technical field of electron yield detection, in particular to a channel electron multiplier and an ultraviolet electron spectrum analyzer. Background Art

[0002] Electron multiplier is a vacuum electron multiplier device with multiplication and amplification function, which can detect extremely weak small signals, such as photons, electrons, ions, α, β, X-rays, etc. Channel electron multiplier is a type of electron multiplier device. Due to its high gain, small size and electron counting ability, it is widely used in space physics, nuclear physics, plasma physics, aerospace and analytical physics.

[0003] The electron collection efficiency is the ratio of the number of photoelectrons effectively multiplied by the channel electron multiplier to the number of photoelectrons emitted from the surface of the measured sample. Its level directly affects the detection efficiency and detection capability of the equipment. Therefore, it is very necessary to design a channel electron multiplier with high collection efficiency. Summary of the invention

[0004] The invention provides a channel electron multiplier and an ultraviolet photoelectron spectrum analyzer, which are used to improve the collection efficiency of the channel electron multiplier and the detection capability of the ultraviolet photoelectron spectrum analyzer.

[0005] The present invention provides a channel electron multiplier, comprising: a channel electron multiplier body and a first focusing electrode connected to the entrance position of the channel electron multiplier body; wherein the first focusing electrode is a hollow ring, the outer edge size is larger than the entrance size of the channel electron multiplier body, the voltage is less than or equal to the input voltage of the channel electron multiplier body, and is used to attract the emitted electrons of the measured sample to the entrance of the channel electron multiplier body.

[0006] A channel electron multiplier provided according to the present invention further includes: a first insulating support sleeve, through which the first focusing electrode is sleeved on the periphery of the inlet of the channel electron multiplier body.

[0007] A channel electron multiplier provided according to the present invention also includes: a second focusing electrode and a second insulating support sleeve, wherein the second focusing electrode is sleeved on the periphery of the first focusing electrode through the second insulating support sleeve, and the voltage of the second focusing electrode is lower than the voltage of the first focusing electrode.

[0008] According to a channel electron multiplier provided by the present invention, the first focusing electrode is a circular ring electrode.

[0009] According to a channel electron multiplier provided by the present invention, the inner diameter of the first focusing electrode is greater than or equal to the outer diameter of the inlet of the channel electron multiplier body 1-6mm, and the outer diameter of the first focusing electrode is greater than or equal to the inner diameter of the first focusing electrode 1-6mm.

[0010] According to a channel electron multiplier provided by the present invention, the second focusing electrode is a circular ring electrode.

[0011] According to a channel electron multiplier provided by the present invention, the inner diameter of the second focusing electrode is greater than or equal to the outer diameter of the first focusing electrode by 1-6 mm, and the outer diameter of the second focusing electrode is greater than or equal to the inner diameter of the second focusing electrode by 1-6 mm.

[0012] According to a channel electron multiplier provided by the present invention, the voltage range of the first focusing electrode is 0V to 1000V.

[0013] According to a channel electron multiplier provided by the present invention, the voltage range of the second focusing electrode is -50V to 0V.

[0014] The present invention also provides an ultraviolet photoelectron spectrum analyzer, comprising: an ultraviolet light source, a vacuum container cover, a supply electrode, an anode and a channel electron multiplier provided by the present invention; The channel electron multiplier is arranged in the vacuum container cover and is powered by the supply electrode; The measurement sample generates photoelectrons under the irradiation of the ultraviolet light source, the channel electron multiplier collects and multiplies the photoelectrons, and the anode collects the output electrons of the channel electron multiplier for electron yield analysis.

[0015] The channel electron multiplier provided by the present invention directly sets the first focusing electrode at the entrance of the channel electron multiplier body, so that the emitted electrons of the measured sample are attracted and gathered by the first focusing electrode and directly enter the entrance of the channel electron multiplier, thereby avoiding the loss of electrons and ensuring the electron collection efficiency. At the same time, the outer diameter of the first focusing electrode is larger than the entrance size of the channel electron multiplier body, which expands the electron attraction range of the channel electron multiplier body and thus improves the electron collection efficiency. Based on this, the ultraviolet electron spectrum analyzer including the channel electron multiplier also improves its detection capability to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 Schematic diagram of the structure of the channel electron multiplier in an embodiment of the present invention.

[0018] Figure 2 Schematic diagram of the structure of the ultraviolet photoelectron spectrum analyzer in an embodiment of the present invention.

[0019] Reference numerals: 1. Second focusing electrode; 2. Second insulating sleeve; 3. First focusing electrode; 4. First insulating sleeve; 5. Channel electron multiplier body; 6. Metal support tube; 7. Anode; 8. Measurement sample; 9. Vacuum container cover; 10. Signal lead wire. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Combine the following Figure 1 The channel electron multiplier of the present invention is described.

[0022] Figure 1 Schematic diagram of the structure of the channel electron multiplier provided by the present invention, such as Figure 1 As shown, the channel electron multiplier includes a channel electron multiplier body 5 and a first focusing electrode 3 connected to the entrance position of the channel electron multiplier body 5; wherein the first focusing electrode 3 is a hollow ring, the outer edge size is larger than the entrance size of the channel electron multiplier body 5, and the voltage is less than or equal to the input voltage of the channel electron multiplier body 5, and is used to attract the emitted electrons of the measurement sample 8 to the entrance of the channel electron multiplier body 5.

[0023] In the embodiment of the present invention, the measurement sample 8 is usually a material with photoelectron emission characteristics such as metal, which generates photoelectrons after receiving light (the light here can be ultraviolet light, and the generated photoelectrons can be called emitted electrons). The emitted electrons are attracted and gathered by the first focusing electrode 3, and then enter the entrance of the channel electron multiplier body 5 through the annular hollow position of the first focusing electrode 3.

[0024] In the embodiment of the present invention, the first focusing electrode 3 is directly disposed at the entrance of the channel electron multiplier body 5, so that the emitted electrons of the measurement sample 8, after being attracted and gathered by the first focusing electrode 3, directly enter the entrance of the channel electron multiplier body 5, thereby avoiding the loss of electrons and thus ensuring the electron collection efficiency. At the same time, the outer diameter of the first focusing electrode 3 is larger than the entrance size of the channel electron multiplier body 5, thereby expanding the electron attraction range of the channel electron multiplier body 5 and thus improving the electron collection efficiency.

[0025] In some embodiments, the channel electron multiplier further includes a first insulating support sleeve 4, and the first focusing electrode 3 is sleeved on the periphery of the entrance of the channel electron multiplier body 5 through the first insulating support sleeve 4. The first insulating support sleeve 4 not only insulates the first focusing electrode 3 from the channel electron multiplier body 5, but also supports the first focusing electrode 3.

[0026] In the embodiment of the present invention, the first focusing electrode 3 can be a circular electrode. In order to ensure the electron collection efficiency, the inner diameter of the first focusing electrode 3 can be greater than or equal to the outer diameter of the entrance of the electron multiplier body 5 1-6mm, and the outer diameter of the first focusing electrode 3 can be greater than or equal to the inner diameter of the first focusing electrode 3 1-6mm.

[0027] In some embodiments, the first focusing electrode 3 may also be in other shapes, such as a square ring electrode, an elliptical ring electrode, etc.; the inner ring and outer ring of the first focusing electrode 3 may be the same or different in shape, for example, they may both be elliptical, or the inner ring (outer ring) may be elliptical and the outer ring (inner ring) may be square, and the present invention does not impose any limitation on this.

[0028] In another embodiment of the present invention, a second focusing electrode 1 and a second insulating support sleeve 2 are also provided at the entrance of the channel electron multiplier body 5. The second focusing electrode 1 is sleeved on the periphery of the first focusing electrode 3 through the second insulating support sleeve 2, and the voltage of the second focusing electrode 1 is lower than the voltage of the first focusing electrode 3.

[0029] In this embodiment, the second insulating support sleeve 2 not only serves to insulate the first focusing electrode 3 from the second focusing electrode 1 , but also serves to support the second focusing electrode 1 .

[0030] When the emitted electrons gather to the first focusing electrode 3, some of the electrons will hit the first focusing electrode 3 and thus cannot enter the entrance of the channel electron multiplier body 5. The purpose of setting the second focusing electrode 1 is to drive these electrons to enter the entrance of the channel electron multiplier body 5. Specifically, the second focusing electrode 1 is sleeved on the periphery of the first focusing electrode 3, and the voltage is lower than the first focusing electrode 3, which will generate a potential difference between the first focusing electrode 3 and the second focusing electrode 1. The electrons that hit the first focusing electrode 3 and the second focusing electrode 1 will gather toward the entrance of the channel electron multiplier body 5 under the action of the potential difference. At the same time, the electrons that hit the first focusing electrode 3 and the second focusing electrode 1 will also achieve a certain degree of effective multiplication due to the collision with the first focusing electrode 3 and the second focusing electrode 1.

[0031] In an embodiment of the present invention, the second focusing electrode 1 may be a circular electrode. To ensure the electron collection efficiency, the inner diameter of the second focusing electrode 1 may be greater than or equal to the outer diameter of the first focusing electrode 3 by 1-6 mm, and the outer diameter of the second focusing electrode 1 may be greater than or equal to the inner diameter of the second focusing electrode 1 by 1-6 mm.

[0032] In some embodiments, the second focusing electrode 1 may also be in other shapes, such as a square ring electrode, an elliptical ring electrode, etc.; the inner ring and outer ring of the second focusing electrode 1 may be the same or different in shape, for example, they may both be elliptical, or the inner ring (outer ring) may be elliptical and the outer ring (inner ring) may be square, and the present invention does not impose any limitation on this.

[0033] In some embodiments, the channel electron multiplier body 5 may include a bell mouth structure and a spiral channel straight tube structure, the upper edge of the bell mouth structure has an input electrode, the end of the spiral channel straight tube structure has an output electrode, and the input voltage is lower than the output voltage. Among them, the number of spiral channels can be 1 or more. The inner surface of the bell mouth and the inner wall of the spiral channel of the channel electron multiplier can be covered with a high secondary electron emission material layer, and the high secondary electron emission material can be selected from one of Al2O3 or MgO materials, and the coating method can be selected from atomic layer deposition coating.

[0034] The ultraviolet electron spectrum analyzer provided by the present invention is described below. Figure 2 The schematic diagram of the structure of the ultraviolet photoelectron spectrum analyzer in the embodiment of the present invention. The ultraviolet photoelectron spectrum analyzer includes the channel electron multiplier, ultraviolet light source, anode 7, supply electrode and vacuum container cover 9 described above. The channel electron multiplier is arranged in the vacuum container cover and powered by the supply electrode. The measurement sample generates photoelectrons under the irradiation of the ultraviolet light source, the channel electron multiplier collects and multiplies the photoelectrons, the anode collects the output electrons of the channel electron multiplier, and the collected electrons are used for subsequent electron yield analysis.

[0035] In this embodiment, the vacuum container cover 9 is the vacuum system of the ultraviolet photoelectron spectrum analyzer. The vacuum container cover 9 can be made of stainless steel, with an electric potential of 0V. Its thickness, size, and structure can be determined according to the actual structure of the ultraviolet photoelectron spectrum analyzer. The vacuum container cover 9 in this embodiment is a spherical cavity structure. In other embodiments, the vacuum container cover 9 can also be a cavity structure of other shapes.

[0036] In this embodiment, the measurement sample 8 is located at the positive spherical center of the vacuum container cover 9, and is used to receive ultraviolet light and generate photoelectrons; the channel electron multiplier is placed in the vacuum container cover 9, forming an angle of 30° with the measurement sample stage, and is used to collect and multiply the photoelectrons emitted by the measurement sample 8; the anode 7 is placed directly behind the output end of the channel electron multiplier, and is used to collect the multiplied electrons output by the channel electron multiplier, and lead out the collected electrical signals through the signal lead-out line 10; the channel electron multiplier and the anode 7 are both powered by the supply electrode.

[0037] It should be noted that the angle between the channel electron multiplier and the measurement sample stage can be adjusted according to the actual application situation, depending on the layout space of the ultraviolet photoelectron spectrum analyzer.

[0038] In an embodiment of the present invention, the anode 7 is usually a copper sheet, a stainless steel sheet or other metal materials with good conductivity. The diameter of the anode 7 should be greater than or equal to the outer diameter of the straight tube part of the channel electron multiplier. In this embodiment, it is 10 mm. The potential of the anode 7 is the highest, and the potential difference with the output electrode of the channel electron multiplier can be 50~500V.

[0039] In this embodiment, the channel electron multiplier and the anode 7 are both at an angle of 30° to the horizontal plane of the measurement sample 8, and are fixed together by a metal support tube 6 and an insulating screw. The electrode and the signal lead wire 10 are placed in the metal support tube 6, and the signal lead wire 10 leads out the electrical signal collected by the anode 7.

[0040] It should be noted that the bell mouth structure of the channel electron multiplier body 5 and the number and size of the spiral channels depend on the specific requirements of the ultraviolet photoelectron spectrum analyzer for gain. For example, the bell mouth opening angle can be 30° or 40°, and the number of spiral channels can be 1 or more. In this embodiment, the bell mouth opening angle of the channel electron multiplier body 5 is 28°, the bell mouth opening diameter is 14 mm, the number of spiral channels is 1, and the diameter of the spiral channel is 0.6 mm.

[0041] In this embodiment, in order to obtain an ideal multiplication effect, the input voltage of the channel electron multiplier body 5 can be adjusted between 0 and 300V, and the output voltage of the channel electron multiplier body 5 can be adjusted between 2300 and 3000V.

[0042] In this embodiment, in order to obtain an ideal electron collection efficiency, the inner diameter of the first focusing electrode 3 is 17 mm, the outer diameter is 18 mm, and the potential range of the first focusing electrode 3 is 0 V to 1000 V. The inner diameter of the second focusing electrode 1 is 21 mm, the outer diameter is 24 mm, and the potential range is -50 V to 0 V.

[0043] For the ultraviolet photoelectron spectrum analyzer provided in the embodiment of the present invention, when the photoelectrons are emitted from the surface of the measurement sample, their movement trajectories are divided into three types: the first part directly enters the channel of the channel electron multiplier body 5 and is effectively multiplied; the second part hits the inner wall of the bell mouth of the channel electron multiplier body 5 and is effectively multiplied; the third part hits the inner wall of the first focusing electrode 3 and the second focusing electrode 1 and is effectively multiplied. Since the voltage of the second focusing electrode 1 is lower than that of the first focusing electrode 3, the electrons of the third part eventually enter the channel of the channel electron multiplier body 5, that is, the photoelectrons of the three parts will be effectively multiplied, thereby effectively ensuring the detection capability of the ultraviolet photoelectron spectrum analyzer.

[0044] Finally, the finite integration method is used to simulate the electron collection efficiency of the ultraviolet photoelectron spectrum analyzer described in the embodiment of the present invention, and the results are as follows: When the first focusing electrode 3 and the second focusing electrode 1 are not present and the input voltage of the channel electron multiplier body 5 is 0V, the photoelectron collection efficiency is 0%.

[0045] When the first focusing electrode 3 and the second focusing electrode 1 are not present, when the input voltage of the channel electron multiplier body 5 is 100V, the photoelectron collection efficiency is 85.6%.

[0046] When the voltage of the first focusing electrode 3 and the input voltage of the channel electron multiplier body 5 are both 100V and the voltage of the second focusing electrode 1 is 0V, the photoelectron collection efficiency is 92.6%.

[0047] When the voltage of the first focusing electrode 3 and the input voltage of the channel electron multiplier body 5 are both 200V and the voltage of the second focusing electrode 1 is 0V, the photoelectron collection efficiency is 100%.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A channel electron multiplier, characterized in that: include: A channel electron multiplier body and a first focusing electrode connected to the entrance of the channel electron multiplier body; wherein the first focusing electrode is a hollow ring, the outer edge size is larger than the entrance size of the channel electron multiplier body, the voltage is less than or equal to the input voltage of the channel electron multiplier body, and is used to attract the emitted electrons of the measured sample to the entrance of the channel electron multiplier body.

2. The channel electron multiplier according to claim 1, characterized in that: Also includes: A first insulating support sleeve, through which the first focusing electrode is sleeved on the periphery of the entrance of the channel electron multiplier body.

3. The channel electron multiplier according to claim 1, characterized in that: Also includes: A second focusing electrode and a second insulating support sleeve, wherein the second focusing electrode is sleeved on the periphery of the first focusing electrode through the second insulating support sleeve, and a voltage of the second focusing electrode is lower than a voltage of the first focusing electrode.

4. The channel electron multiplier according to claim 1, characterized in that: The first focusing electrode is a ring-shaped electrode.

5. The channel electron multiplier according to claim 4, characterized in that: The inner diameter of the first focusing electrode is greater than or equal to the outer diameter of the inlet of the channel electron multiplier body, which is 1-6 mm, and the outer diameter of the first focusing electrode is greater than or equal to the inner diameter of the first focusing electrode, which is 1-6 mm.

6. The channel electron multiplier according to claim 3, characterized in that: The second focusing electrode is a ring-shaped electrode.

7. The channel electron multiplier according to claim 6, characterized in that: The inner diameter of the second focusing electrode is greater than or equal to the outer diameter of the first focusing electrode by 1-6 mm, and the outer diameter of the second focusing electrode is greater than or equal to the inner diameter of the second focusing electrode by 1-6 mm.

8. The channel electron multiplier according to any one of claims 3 to 7, characterized in that: The voltage range of the first focusing electrode is 0V to 1000V.

9. The channel electron multiplier according to claim 8, characterized in that: The voltage range of the second focusing electrode is -50V to 0V.

10. An ultraviolet photoelectron spectrum analyzer, characterized in that: include: An ultraviolet light source, a vacuum container cover, a supply electrode, an anode, and a channel electron multiplier as described in any one of claims 1 to 9; The channel electron multiplier is arranged in the vacuum container cover and is powered by the supply electrode; The measurement sample generates photoelectrons under the irradiation of the ultraviolet light source, the channel electron multiplier collects and multiplies the photoelectrons, and the anode collects the output electrons of the channel electron multiplier for electron yield analysis.

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