Device for improving collection efficiency of channel electron multiplier in ultraviolet electron spectrum analyzer

Abstract

The invention discloses a device for improving the collection efficiency of a channel electron multiplier in an ultraviolet electron spectrum analyzer. The device comprises a focusing electrode, an insulating spacer, a metal protection barrel, an anode and a power supply and signal lead-out wire, the channel electron multiplier is arranged in the metal protection barrel; the focusing electrode is positioned between an opening of the channel electron multiplier and a sample to be detected; an anode is arranged at the rear end of the channel electron multiplier and is connected with a power supply and signal lead-out wire; an insulating spacer is arranged between the focusing electrode and the channel electron multiplier, one end of the insulating spacer is connected with the focusing electrode, and the other end of the insulating spacer is connected with the channel electron multiplier. Through electric field guiding and precise structural design, the problem of low electron collection efficiency is systematically solved, and a reliable technical scheme is provided for high-precision photoelectron spectrum analysis.

Description

Technical Field

[0001] The present invention relates to the field of photoelectric detection technology, and in particular to a device for improving the collection efficiency of a channel electron multiplier in an ultraviolet photoelectron spectrum analyzer. Background Art

[0002] Ultraviolet photoelectron spectroscopy (UPS) analyzer is an instrument for studying the electronic structure of material surfaces. It is widely used in electron energy state analysis, surface chemical analysis, aerospace material evaluation, semiconductor device optimization, etc.

[0003] Ultraviolet photoelectron spectrometers are used to measure the photoelectron emission yield spectrum of materials in the ultraviolet band. This yield is determined by calculating the ratio of the number of photoelectrons emitted per unit surface area and per unit time to the number of incident photons. Therefore, the analyzer must be able to accurately measure the number of photons and photoelectrons corresponding to the wavelength of the incident light.

[0004] The photoelectron count is measured using a channel electron multiplier. Light from a deuterium lamp is split by a monochromator and then enters the vacuum system. It illuminates the sample stage, stimulating photoelectrons. Some of these photoelectrons are collected and multiplied by the electric field at the entrance of the channel electron multiplier. The multiplied electrons are then collected by the anode and transmitted via a signal line to a photoelectron counter outside the vacuum chamber for precise counting.

[0005] The photoelectron collection efficiency (PCE) is the ratio of the number of photoelectrons collected by the CEM to the number of photoelectrons emitted by the sample surface. Collection is crucial for accurately measuring the photoelectron emission yield spectrum and directly impacts the instrument's detection efficiency and capabilities. Due to the influence of the photoelectron emission angle and energy, as well as the CEM input voltage, not all photoelectrons are captured by the CEM. Considering the overall energy consumption of the UV photoelectron spectrum analyzer, the CEM input voltage should not be too high. Summary of the Invention

[0006] The purpose of the present invention is to provide a device for improving the collection efficiency of a channel electron multiplier in an ultraviolet electron spectrum analyzer, which is mainly used when the input voltage of the channel electron multiplier is low (not exceeding 200V).

[0007] To achieve the above object, the technical solution provided by the present invention is:

[0008] A device for improving the collection efficiency of a channel electron multiplier in an ultraviolet electron spectrum analyzer, characterized in that it comprises: a focusing electrode, an insulating gasket, a metal protection barrel, an anode, and power supply and signal lead wires;

[0009] The channel electron multiplier is placed in a metal protective barrel, and the focusing electrode is located between the opening of the channel electron multiplier and the sample to be tested; an anode is provided at the rear end of the channel electron multiplier, and the anode is connected to a power supply and signal lead wire;

[0010] An insulating gasket is provided between the focusing electrode and the channel electron multiplier. One end of the insulating gasket is connected to the focusing electrode, and the other end is connected to the channel electron multiplier.

[0011] To optimize the above technical solutions, specific limitations also include:

[0012] The focusing electrode is in the shape of a hollow semi-cylinder electrode.

[0013] Furthermore, the shape of the insulating gasket is also a hollow semi-cylinder, and the inner diameter, outer diameter and bow height of the whole circle are consistent with the corresponding parameters of the focusing electrode.

[0014] Preferably, the insulating gasket is made of plastic and has a length not exceeding 3 mm.

[0015] Furthermore, the input voltage of the channel electron multiplier is not higher than 200V.

[0016] Furthermore, the inner diameter of the focusing electrode is greater than or equal to the outer diameter of the opening of the channel electron multiplier.

[0017] Preferably, the outer diameter of the entire circle where the focusing electrode is located is equal to the outer diameter of the metal protective barrel.

[0018] Furthermore, the bow height of the focusing electrode is not greater than its inner diameter and not less than the difference between its outer diameter and inner diameter.

[0019] Furthermore, the focusing electrode does not contact the sample stage in the ultraviolet photoelectron spectrum analyzer.

[0020] Furthermore, the voltage of the focusing electrode is greater than 0V and does not exceed the input voltage of the channel electron multiplier.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention systematically solves the problem of low electron collection efficiency through electric field guidance and precise structural design, providing a reliable technical solution for high-precision photoelectron spectrum analysis:

[0023] The focusing electrode of the present invention is placed in front of the opening of the channel electron multiplier in the ultraviolet photoelectron spectrum analyzer and close to the sample to be tested. When the light emitted by the deuterium lamp enters the vacuum chamber after being split by the monochromator, it irradiates the sample to be tested to excite photoelectrons. The emitted photoelectrons are attracted and focused by the device, enter the entrance of the channel electron multiplier, multiply therein, and are finally collected by the anode. The presence of the focusing electrode avoids the loss of electrons, improves the collection efficiency of the channel electron multiplier, ensures the measurement accuracy of the photoelectron spectrometer, and reduces the overall energy consumption of the ultraviolet photoelectron spectrum analyzer.

[0024] The present invention has a compact structure and is compatible with existing ultraviolet electron spectrometers without requiring major modifications. By reducing electron loss and enhancing weak signal detection capabilities, the present invention is suitable for low-concentration or surface-sensitive analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The invention relates to a focusing electrode, an insulating gasket and a channel electron multiplier.

[0026] Figure 2 The diagram is a structural diagram of a device for improving the collection efficiency of a channel electron multiplier in an ultraviolet electron spectrum analyzer according to the present invention.

[0027] In the figure: 1-focusing electrode; 2-insulating gasket; 3-channel electron multiplier; 4-metal protection barrel; 5-anode; 6-sample to be tested; 7-vacuum chamber; 8-power supply and signal lead wires. DETAILED DESCRIPTION

[0028] The above contents of the present invention are further described in detail below in the form of specific implementation methods, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments. All technologies implemented based on the above contents of the present invention belong to the scope of the present invention.

[0029] The orientation or position relationship is based on the relationship shown in the drawings and is only for the convenience of describing the present invention and simplifying the description. It does not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it should not be understood as a limitation on the present invention.

[0030] The present invention provides a device for improving the collection efficiency of a channel electron multiplier 3 in an ultraviolet electron spectrum analyzer, comprising: a focusing electrode 1, an insulating gasket 2, a metal protection barrel 4, an anode 5, and power supply and signal lead wires 8;

[0031] The channel electron multiplier 3 is placed in a metal protective barrel 4, and the focusing electrode 1 is located between the opening of the channel electron multiplier 3 and the sample to be measured 6; an anode 5 is provided at the rear end of the channel electron multiplier 3, and the anode 5 is connected to a power supply and signal lead 8;

[0032] like Figure 1 As shown, an insulating gasket 2 is provided between the focusing electrode 1 and the channel electron multiplier 3 , one end of the insulating gasket 2 is connected to the focusing electrode 1 , and the other end is connected to the channel electron multiplier 3 .

[0033] The focusing electrode 1 is in the shape of a hollow semi-cylinder electrode. The hollow semi-cylinder electrode has a simple design structure and can construct an accelerating and focusing electric field near the sample stage, which is beneficial to the collection of photoelectrons.

[0034] Furthermore, the shape of the insulating gasket 2 is also a hollow semi-cylinder, and the inner diameter, outer diameter and bow height of the entire circle of the semi-cylinder are consistent with the corresponding parameters of the focusing electrode 1; the shape of the insulating gasket is consistent with the focusing electrode, and can isolate the focusing electrode and the shielding barrel (grounded) so that voltage can be applied to the focusing electrode.

[0035] The insulating spacer 2 is made of plastic and has a length not exceeding 3 mm.

[0036] In some embodiments, the input voltage of the channel electron multiplier 3 is not higher than 200V and is adjustable from 0V to 200V.

[0037] The inner diameter of the focusing electrode 1 is greater than or equal to the outer diameter of the opening of the channel electron multiplier 3 .

[0038] In some embodiments, the outer diameter of the entire circle where the focusing electrode 1 is located is equal to the outer diameter of the metal protection barrel 4 .

[0039] The height of the focusing electrode 1 is not greater than its inner diameter and not less than the difference between its outer diameter and inner diameter.

[0040] The focusing electrode 1 does not contact the sample stage in the ultraviolet photoelectron spectrum analyzer; the sample stage is grounded and has a voltage of 0V, and the voltage of the focusing electrode 1 is greater than 0V, so they cannot contact each other.

[0041] The voltage of the focusing electrode 1 is greater than 0V and does not exceed the input voltage of the channel electron multiplier 3 .

[0042] The present invention guides the electron beam emitted by the sample through the electric field gradient generated by the focusing electrode 1, so that it efficiently enters the entrance of the channel electron multiplier 3, combines insulation isolation and structural matching design to reduce electron loss, thereby improving signal collection efficiency.

[0043] The hollow, semi-cylinder-shaped focusing electrode 1 generates a radially symmetric electric field, converging the electron path toward the center of the channel. This semi-cylinder shape optimizes the electric field distribution and enhances the focusing of edge electrons. Bow height constraints balance focusing capability with space usage, ensuring maximum geometric focusing.

[0044] The insulating spacer 2 of the present invention not only isolates the focusing electrode 1 from the multiplier to prevent leakage, but also ensures electric field continuity through matching shapes. The insulating spacer 2 has high insulation properties and high voltage resistance, preventing interference. Its length is limited, minimizing the surface area of the insulator and reducing the risk of charge accumulation.

[0045] The metal protection barrel 4 of the present invention is electromagnetically shielded to prevent external interference, mechanically protects the multiplier, and may be grounded to stabilize the potential.

[0046] The input voltage of the channel electron multiplier 3 of the present invention is ≤200V, and the low voltage design avoids focusing failure or multiplier overload caused by excessive electron velocity, and balances gain and controllability.

[0047] The positive voltage of focusing electrode 1 attracts electrons, forming a potential gradient from the sample to the multiplier, guiding the electrons to enter efficiently.

[0048] The focusing electrode 1 and the insulating gasket 2 of the present invention have consistent shapes, which can ensure seamless transition of the electric field and reduce scattering; the focusing electrode 1 is independent of the sample stage, avoiding sample potential disturbance and ensuring measurement accuracy.

[0049] The structure of the invention is compact, and it is adapted to the existing ultraviolet electron spectrometer without requiring major modification, and it has high compatibility.

[0050] The present invention reduces electron loss and enhances weak signal detection capability, and is suitable for low-concentration or surface-sensitive analysis.

[0051] In summary, the present invention systematically solves the problem of low electron collection efficiency through electric field guidance and precise structural design, and provides a reliable technical solution for high-precision photoelectron spectroscopy analysis.

[0052] The focusing electrode 1 of the present invention is placed in front of the opening of the channel electron multiplier 3 in the ultraviolet photoelectron spectrum analyzer, near the sample 6 to be tested. When the light emitted by the deuterium lamp is split by the monochromator and enters the vacuum chamber 7, it irradiates the sample 6 to be tested and excites photoelectrons. The emitted photoelectrons are attracted and focused by the device, enter the entrance of the channel electron multiplier 3, and multiply therein. They are finally collected by the anode 5 and transmitted to the photoelectron counter outside the vacuum chamber 7 via the power supply and signal lead wires 8 for accurate counting. The presence of the focusing electrode 1 avoids electron loss, improves the collection efficiency of the channel electron multiplier 3, ensures the measurement accuracy of the photoelectron spectrometer, and reduces the overall energy consumption of the ultraviolet photoelectron spectrum analyzer.

[0053] The technical solution of the present invention is further described in detail below with reference to specific embodiments:

[0054] like Figure 2As shown, the channel electron multiplier 3 is placed in a metal protective barrel 4. The focusing electrode 1 is connected to the inlet of the channel electron multiplier 3 via an insulating gasket 2. The anode 5 is located near the output end of the channel electron multiplier 3, and the power supply and signal lead 8 is connected to the anode 5. The focusing electrode 1, insulating gasket 2, channel electron multiplier 3, metal protective barrel 4, and anode 5 are assembled into a whole and placed near the sample 6 to be tested in the vacuum chamber 7 of the ultraviolet photoelectron spectrum analyzer.

[0055] The channel electron multiplier 3 is used to collect and multiply photoelectrons emitted by the sample 6 to be tested. It consists of a bell mouth and a multiplication channel. The multiplication channel can be a spiral channel or a curved channel. In this embodiment, a spiral channel structure is used. The lower edge of the bell mouth is connected to the multiplication channel, and the outer diameter of the upper edge is larger than the lower edge. In this embodiment, the outer diameter of the upper edge of the bell mouth is 13.68 mm. The bell mouth opening angle is adjustable from 20° to 50°. In this embodiment, the bell mouth opening angle is 28°. The inner surface of the bell mouth and the inner wall of the multiplication channel are uniformly coated with a high secondary electron emission material such as Al2O3 or MgO using atomic layer deposition. In this embodiment, Al2O3 is used. The upper edge of the bell mouth has an input electrode, and the end of the multiplication channel has an output electrode. The output voltage maintains an adjustable potential difference of 1000V to 3000V relative to the input voltage. In this embodiment, 2000V is used. Considering the overall energy consumption of the ultraviolet photoelectron spectrum analyzer, the input voltage of the channel electron multiplier 3 is not higher than 200V. In this embodiment, it is 200V.

[0056] The inner diameter of the metal protective barrel 4 is larger than the outer diameter of the bell mouth of the channel electron multiplier 3, and the difference between the outer and inner diameters does not exceed 5 mm. In this embodiment, the inner diameter of the metal protective barrel 4 is 18 mm and the outer diameter is 20 mm. To avoid affecting the collection of electrons by the channel electron multiplier 3, the metal protective barrel 4 is grounded.

[0057] The focusing electrode 1 is a hollow semi-circular barrel electrode, the inner diameter of which is greater than or equal to the outer diameter of the trumpet mouth of the channel electron multiplier 3, and the outer diameter is equal to the outer diameter of the metal protective barrel 4. In this embodiment, the inner diameter of the focusing electrode 1 is 18 mm, and the outer diameter is 20 mm. The bow height of the focusing electrode 1 is not greater than its inner diameter, and not less than the difference between its outer diameter and inner diameter. In this embodiment, the bow height of the focusing electrode 1 is 10 mm. The focusing electrode cannot contact the sample stage in the ultraviolet photoelectron spectrum analyzer at most. In this embodiment, the length of the focusing electrode 1 is 20 mm. The voltage of the focusing electrode 1 is greater than 0 V, and does not exceed the input voltage of the channel electron multiplier 3. In this embodiment, the voltage of the focusing electrode 1 is 50 V.

[0058] The insulating spacer 2 is a hollow semi-circular barrel, one side of which is connected to the metal protective barrel 4 of the channel electron multiplier 3 and the other side to the focusing electrode 1. The insulating spacer 2 is made of an insulating material, in this embodiment, plastic PEEK. The inner diameter, outer diameter, and bow height of the insulating spacer 2 are consistent with those of the focusing electrode 1, and its length does not exceed 3 mm. In this embodiment, the inner diameter, outer diameter, bow height, and length of the insulating spacer 2 are 18 mm, 20 mm, 10 mm, and 1 mm, respectively.

[0059] The anode 5 is placed directly behind the output terminal of the channel electron multiplier 3 and is used to collect the multiplied electrons output by the channel electron multiplier 3. It is typically circular in shape, with a diameter larger than the outer diameter of the multiplication channel of the channel electron multiplier 3 and smaller than the inner diameter of the metal protective barrel 4. In this embodiment, the diameter of the anode 5 is 12 mm. It is made of stainless steel or other highly conductive metal materials. The voltage of the anode 5 is 100V to 500V higher than the output voltage of the channel electron multiplier 3. In this embodiment, the voltage of the anode 5 is 200V higher than the output voltage of the channel electron multiplier 3.

[0060] The power supply and signal lead-out line 8 is connected to the anode 5 to lead out the collected electrical signal; the power supply and signal lead-out line 8 simultaneously supplies power to the channel electron multiplier and the anode 5 .

[0061] The outer shell of the vacuum chamber 7 of the ultraviolet electron spectrum analyzer is made of metal and is vacuum inside. In order to avoid affecting the collection of electrons by the channel electron multiplier 3, the outer shell of the vacuum chamber 7 is grounded.

[0062] The sample 6 is placed in the vacuum chamber 7 of the UV photoelectron spectrometer, located at the center of the sphere in this embodiment, to receive UV light and generate photoelectrons. The angle between the channel electron multiplier 3 and the sample 6 can be adjusted according to the actual application, specifically depending on the layout space of the UV photoelectron spectrometer. In this embodiment, this angle is 30°.

[0063] Based on the above scheme, the focusing electrode 1 of the present invention is placed in front of the horn of the channel electron multiplier 3 in the ultraviolet photoelectron spectrum analyzer, near the sample stage to be tested. When the light emitted by the deuterium lamp is separated by the monochromator and enters the vacuum chamber 7, it irradiates the sample to be tested to excite photoelectrons. The emitted photoelectrons are attracted and focused by the device, enter the horn of the channel electron multiplier 3, and are multiplied therein. They are finally collected by the anode 5 and transmitted to the photoelectron counter outside the vacuum chamber 7 through the power supply and signal lead wire 8 for accurate counting. The presence of the focusing electrode avoids electron loss, improves the collection efficiency of the channel electron multiplier, ensures the measurement accuracy of the photoelectron spectrometer, and reduces the overall energy consumption of the ultraviolet photoelectron spectrum analyzer.

[0064] The electron collection efficiency of the embodiment of the present invention was simulated using the finite integration method, and the results are as follows:

[0065] When there is no focusing electrode 1 and the input voltage of the channel electron multiplier 3 is 0V, the photoelectron collection efficiency is 0%.

[0066] When there is no focusing electrode 1 and the input voltage of the channel electron multiplier 3 is 100 V, the photoelectron collection efficiency is 85.8%.

[0067] When there is no focusing electrode 1 and the input voltage of the channel electron multiplier 3 is 200 V, the photoelectron collection efficiency is 91.3%.

[0068] When the input voltage of the focusing electrode 1 is 30V and the input voltage of the channel electron multiplier 3 is 200V, the photoelectron collection efficiency is 94.6%.

[0069] When the input voltage of the focusing electrode 1 is 50V and the input voltage of the channel electron multiplier body 3 is 200V, the photoelectron collection efficiency is 100%.

[0070] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modification, equivalent replacement and improvement made by any technician familiar with the profession to the above embodiment without departing from the scope of the technical solution of the present invention and based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A device for improving the collection efficiency of a channel electron multiplier in an ultraviolet electron spectrum analyzer, characterized in that: include: Focusing electrode, insulating gasket, metal protection barrel, anode, power supply and signal lead wires; The channel electron multiplier is placed in a metal protective barrel, and the focusing electrode is located between the opening of the channel electron multiplier and the sample to be tested; an anode is provided at the rear end of the channel electron multiplier, and the anode is connected to a power supply and signal lead wire; An insulating gasket is provided between the focusing electrode and the channel electron multiplier. One end of the insulating gasket is connected to the focusing electrode, and the other end is connected to the channel electron multiplier.

2. The device for improving the collection efficiency of a channel electron multiplier in an ultraviolet electron spectrum analyzer according to claim 1, characterized in that: The focusing electrode is in the shape of a hollow semi-cylinder electrode.

3. The device for improving the collection efficiency of a channel electron multiplier in an ultraviolet electron spectrum analyzer according to claim 2, characterized in that: The shape of the insulating gasket is also a hollow semi-cylinder, and the inner diameter, outer diameter and bow height of the whole circle are consistent with the corresponding parameters of the focusing electrode.

4. The device for improving the collection efficiency of a channel electron multiplier in an ultraviolet electron spectrum analyzer according to claim 1, characterized in that: The insulating gasket is made of plastic and has a length not exceeding 3 mm.

5. The device for improving the collection efficiency of a channel electron multiplier in an ultraviolet electron spectrum analyzer according to claim 1, characterized in that: The input voltage of the channel electron multiplier is not higher than 200V.

6. The device for improving the collection efficiency of a channel electron multiplier in an ultraviolet electron spectrum analyzer according to claim 2, characterized in that: The inner diameter of the focusing electrode is greater than or equal to the outer diameter of the opening of the channel electron multiplier.

7. The device for improving the collection efficiency of a channel electron multiplier in an ultraviolet electron spectrum analyzer according to claim 2, characterized in that: The outer diameter of the entire circle where the focusing electrode is located is equal to the outer diameter of the metal protection barrel.

8. The device for improving the collection efficiency of a channel electron multiplier in an ultraviolet electron spectrum analyzer according to claim 2, characterized in that: The bow height of the focusing electrode is not greater than its inner diameter and not less than the difference between its outer diameter and inner diameter.

9. The device for improving the collection efficiency of a channel electron multiplier in an ultraviolet electron spectrum analyzer according to claim 1, characterized in that: The focusing electrode does not contact the sample stage in the ultraviolet photoelectron spectrum analyzer.

10. The device for improving the collection efficiency of a channel electron multiplier in an ultraviolet electron spectrum analyzer according to claim 1, characterized in that: The voltage of the focusing electrode is greater than 0V and does not exceed the input voltage of the channel electron multiplier.

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