A teaching platform for measuring the inversion energy level of ammonia molecules and a method of using the same

Abstract

A teaching platform for measuring ammonia molecular inversion level and a method for using the same, comprising a microwave module, a gas module, a measurement module and a pressurizing module; the microwave module comprises a tunable frequency microwave source for providing an experimental microwave signal with a frequency of 11.0-13.0 GHz, and a pair of symmetrically arranged EH impedance matching devices connected with two horn antennas through straight waveguides, the two horn antennas being symmetrically arranged and spaced apart; the gas module comprises a gas container arranged on one side of the output end of the tunable frequency microwave source and between the two horn antennas, and externally connected with a vacuum pump, a high-voltage DC power supply and an ammonia source; the measurement module is arranged on the side of the gas module away from the microwave module, and comprises a detector connected with the EH impedance matching device away from the tunable frequency microwave source, and the detector is externally connected with an oscilloscope. A teaching platform with low cost but good effect suitable for quantum mechanics related experimental teaching is provided.

Description

Technical Field

[0001] This invention relates to the field of physics experimental teaching instrument platform technology, and in particular to a teaching platform for measuring the inverted energy level of ammonia molecules and its usage method. Background Technology

[0002] Since the beginning of the 21st century, quantum technology has become a key focus of scientific and technological development in various countries. In fields such as quantum computing, quantum communication, and quantum precision measurement, quantum technology has demonstrated technological routes and performance exceeding those permitted by classical physics, becoming a research hotspot in basic science and many military and civilian engineering fields. Understanding and mastering quantum mechanics is gradually becoming an essential knowledge base for physics majors, and even more engineering professionals, thus the teaching of quantum mechanics is receiving increasing attention and importance.

[0003] Because quantum mechanics concepts are abstract and counterintuitive, they are difficult for students to understand and master, making it a challenging topic in physics teaching. Experimental teaching has always been an important aid in helping students understand and accept the abstract concepts of quantum mechanics. However, current university physics experiments involving quantum mechanics suffer from a limited number and insufficient variety of experimental subjects. Existing quantum mechanics experiments mainly include the Franck-Hertz experiment, the photoelectric effect experiment, the Zeeman effect experiment, and the electron spin resonance experiment, primarily using electrons and photons as the experimental subjects. Increasing the number of quantum mechanics experiments, especially those using microscopic particles with relatively large masses and definite geometric shapes and scales such as atoms and molecules as the experimental subjects, would greatly benefit the teaching of quantum mechanics.

[0004] The quantum tunneling effect is a typical example in the teaching of quantum mechanics theory and one of the important problems in the research and verification of quantum mechanics. Therefore, a teaching platform suitable for application in university physics teaching is needed to help students intuitively understand the quantum tunneling effect. Summary of the Invention

[0005] To address the above problems, this invention provides a teaching platform for measuring the inverted energy level of ammonia molecules and its usage method. This invention is implemented as follows:

[0006] A teaching platform for measuring the inverted energy level of ammonia molecules, comprising:

[0007] Microwave module, gas module, measurement module, and pressurization module;

[0008] The microwave module includes,

[0009] A frequency-tunable microwave source is used to provide microwave signals required for experiments at frequencies between 11.0 and 13.0 GHz, wherein the microwave signals are doubled in frequency by a passive frequency multiplier.

[0010] A pair of symmetrically arranged EH impedance modulators are provided. The EH impedance modulators are connected to two horn antennas respectively through straight waveguides. The two horn antennas are symmetrically opposite each other and spaced apart. The EH impedance modulators are used to change the load state of the microwave system. The EH impedance modulators adjust the teaching platform system to a matched, capacitive load or inductive load state.

[0011] The gas module includes,

[0012] A gas container is disposed on one side of the output end of the frequency-tunable microwave source and between the two horn antennas. The gas container is externally connected to a vacuum pump and an ammonia source. The gas container forms a vacuum environment through the vacuum pump, and the ammonia source is used to replenish ammonia in the gas container after evacuation.

[0013] The measurement module is located on the side of the gas module away from the microwave module. The measurement module includes a detector connected to the EH impedance tuner away from the frequency-tunable microwave source. The detector is externally connected to an oscilloscope. The detector couples the induced voltage between the two wide walls from the midpoint of the waveguide wide wall, and detects it through a microwave diode, so that the microwave signal is converted into a DC signal that reflects the microwave intensity.

[0014] The pressurization module includes a high-voltage power supply, which is electrically connected to a pair of electrode plates. The two electrode plates are respectively disposed on the upper and lower surfaces of the gas container. The high-voltage DC power supply is used to provide an external electric field to the ammonia gas in the gas container after it has been evacuated.

[0015] As a further improvement, the gas container is connected to the vacuum pump and the ammonia source respectively through a vacuum rubber tube. Glass valves are also provided between the gas container and the vacuum pump, and between the gas container and the ammonia source. A needle valve is also provided between the gas container and the ammonia source.

[0016] As a further improvement, the output terminal of the detector is connected to a short-circuit piston, which is a single-arm microwave element connected to the terminal of the transmission system. The short-circuit piston reflects the incident microwave power without absorbing it, thereby forming a pure standing wave state in the transmission system.

[0017] As a further improvement, the short-circuit piston is a rectangular waveguide with a movable metal short-circuit surface. The position of the short-circuit surface of the short-circuit piston is adjusted by a screw and can be directly read.

[0018] As a further improvement, the frequency of the microwave signal output after amplification by the passive frequency multiplier is 22-26GHz, the applied electric field strength provided by the high voltage DC power supply is 10000-15000V / m, and the gas container is made of quartz or glass.

[0019] As a further improvement, the amplified output end of the horn antenna completely covers the side wall surface of the gas container.

[0020] This invention also relates to a method of using a teaching platform for measuring the inverted energy level of an ammonia molecule, applied to any of the teaching platforms described above for measuring the inverted energy level of an ammonia molecule, for measuring the (3,3) absorption peak, comprising the following steps:

[0021] S1. Start the oscilloscope and warm it up for 20-40 minutes;

[0022] S2. Adjust the two horn antennas to ensure alignment;

[0023] S3. Place a gas container between the two horn antennas;

[0024] S4. Start the adjustable frequency microwave source and simultaneously adjust the operating voltage of the adjustable frequency microwave source to 5V;

[0025] S5. Adjust the voltage sequentially from small to large between 5.9-7.2V, while simultaneously measuring the microwave frequency with a frequency meter to obtain and record the relationship between the signal voltage V and the microwave frequency f(V).

[0026] S6. Turn on the vacuum pump and ammonia source, turn off the ammonia source after 8-12 minutes, and then turn off the vacuum pump after another 3-7 minutes. Observe and record the pressure value.

[0027] S7. Adjust the voltage sequentially from small to large between 6.1-6.9V, read and record the corresponding readings on the oscilloscope, and obtain the vacuum microwave signal spectrum I0(f);

[0028] S8. Turn on the ammonia source, observe and record the pressure reading, repeat S7, and obtain the ammonia microwave signal spectrum I1(f);

[0029] S9. Calculate the absorption spectrum α(f) of ammonia according to the formula, find the control voltage V and the corresponding frequency corresponding to the (3,3) absorption peak, compare it with the accurate measurement value of the (3,3) absorption peak and calculate the error.

[0030] This invention also relates to a method of using a teaching platform for measuring the inverted energy level of an ammonia molecule, applied to any of the teaching platforms described above for measuring the inverted energy level of an ammonia molecule, for measuring the (6,6) absorption peak, comprising the following steps:

[0031] S1. Start the oscilloscope and warm it up for 20-40 minutes;

[0032] S2. Adjust the two horn antennas to ensure alignment;

[0033] S3. Place a gas container between the two horn antennas;

[0034] S4. Start the adjustable frequency microwave source and simultaneously adjust the operating voltage of the adjustable frequency microwave source to 5V;

[0035] S5. Adjust the voltage from small to large between 9.1-10.0V, and at the same time use a frequency meter to measure the microwave frequency, obtain the relationship between the signal voltage V and the microwave frequency f(V) and record it.

[0036] S6. Turn on the vacuum pump and ammonia source, turn off the ammonia source after 8-12 minutes, and then turn off the vacuum pump after another 3-7 minutes. Observe and record the pressure value.

[0037] S7. Adjust the voltage sequentially from small to large between 9.2-10.3V, read and record the corresponding readings on the oscilloscope, and obtain the vacuum microwave signal spectrum I0(f);

[0038] S8. Turn on the ammonia source, observe and record the pressure reading, repeat S7, and obtain the ammonia microwave signal spectrum I1(f);

[0039] S9. Calculate the absorption spectrum α(f) of ammonia according to the formula, find the control voltage V and the corresponding frequency corresponding to the absorption peak (6,6), compare it with the accurate measurement value of the absorption peak (6,6) and calculate the error.

[0040] S10. Adjust the high voltage power supply to 5000V, the distance between the parallel plates is 7cm, and obtain the electric field strength. Repeat step S7 to obtain the microwave signal spectrum I1(f)' of ammonia under high voltage.

[0041] S11. Calculate the absorption spectrum α(f) of ammonia according to the formula, find the control voltage V and the corresponding frequency corresponding to the absorption peak (6, 6), compare it with the accurate measurement value of the absorption peak (6, 6) and calculate the error.

[0042] The beneficial effects of this invention are as follows:

[0043] Existing university physics teaching experimental platforms involve relatively few quantum mechanics experiments, and the main quantum phenomena involved are only electrons and photons. Traditional equipment for measuring the inverted energy level of ammonia molecules is complex and costly. This invention, however, uses a tunable microwave source with a passive frequency multiplier to amplify the signal, achieving microwave frequency control within a limited range of 22-26 GHz, thus significantly reducing equipment costs. By employing a combination of a horn antenna and an independent gas container, ammonia gas is separated from the metal waveguide, and the metal electrodes generating the electrostatic field are also separated from the waveguide, preventing mutual interference. Then, using high-voltage parallel electrodes, a strong electric field of 10000-15000 V / m is formed within the gas container, enabling control of the inverted energy level. This simplifies the experimental process, greatly reducing equipment requirements and significantly lowering costs. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the overall device module structure of the present invention.

[0045] Figure 2 This is a schematic diagram of the microwave module structure of the present invention.

[0046] Figure 3 The following is a reference diagram showing the relationship between the control voltage and the microwave output frequency of the QM-VCO1113A voltage-controlled oscillator of the present invention.

[0047] Figure 4 This is a schematic diagram showing the two structural states of an ammonia molecule.

[0048] Figure 5 This is a diagram showing the frequency-control voltage relationship in Embodiment 1 of the present invention.

[0049] Figure 6 This is a diagram showing the frequency-control voltage relationship in Embodiment 2 of the present invention.

[0050] Figure 7 This is a graph showing the relationship between absorption rate and control voltage in Embodiment 1 of the present invention, specifically the ammonia absorption spectrum of Embodiment 1.

[0051] Figure 8 This is a graph showing the relationship between absorption rate and control voltage in Example 2 of the present invention, specifically the ammonia absorption spectrum of Example 2.

[0052] Figure 9 This is a graph showing the relationship between absorption rate and control voltage in Embodiment 2 of the present invention at 5000V, specifically the ammonia absorption spectrum of Embodiment 2 at 5000V.

[0053] Figure 10 This is a schematic diagram of the two symmetrical states of an ammonia molecule under an external electric field.

[0054] Figure 11This is a diagram showing the energy level changes of ammonia molecules in an external electric field. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0056] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0057] A teaching platform for measuring the inverted energy level of ammonia molecules, comprising:

[0058] Microwave module, gas module, measurement module, and pressurization module;

[0059] The microwave module includes,

[0060] A frequency-tunable microwave source is used to provide microwave signals required for experiments at frequencies between 11.0 and 13.0 GHz, wherein the microwave signals are doubled in frequency by a passive frequency multiplier.

[0061] A pair of symmetrically arranged EH impedance modulators are provided. The EH impedance modulators are connected to two horn antennas respectively through straight waveguides. The two horn antennas are symmetrically opposite each other and spaced apart. The EH impedance modulators are used to change the load state of the microwave system. The EH impedance modulators adjust the teaching platform system to a matched, capacitive load or inductive load state.

[0062] The gas module includes,

[0063] A gas container is disposed on one side of the output end of the frequency-tunable microwave source and between the two horn antennas. The gas container is externally connected to a vacuum pump and an ammonia source. The gas container forms a vacuum environment through the vacuum pump, and the ammonia source is used to replenish ammonia in the gas container after evacuation.

[0064] The measurement module is located on the side of the gas module away from the microwave module. The measurement module includes a detector connected to the EH impedance tuner away from the frequency-tunable microwave source. The detector is externally connected to an oscilloscope. The detector couples the induced voltage between the two wide walls from the midpoint of the waveguide wide wall, and detects it through a microwave diode, so that the microwave signal is converted into a DC signal reflecting the microwave intensity.

[0065] The pressurization module includes a high-voltage power supply, which is electrically connected to a pair of electrode plates. The two electrode plates are respectively disposed on the upper and lower surfaces of the gas container. The high-voltage DC power supply is used to provide an external electric field to the ammonia gas in the gas container after it has been evacuated.

[0066] As a further improvement, the frequency-tunable microwave source specifically includes:

[0067] A signal generator, which is used to control the magnitude of the input voltage;

[0068] A voltage-controlled oscillator (VCO) is an electronic device that adjusts its output frequency based on an input voltage signal. The input voltage signal is used as a control signal, and the frequency of the VCO circuit is changed by altering the capacitance across a varactor diode.

[0069] Preferably, the voltage-controlled oscillator is a QM-VCO1113A type voltage-controlled oscillator, and the voltage-controlled oscillator is provided with operating voltage by a DC regulated power supply.

[0070] The passive frequency multiplier specifically includes:

[0071] A power amplifier is a circuit that amplifies low-power radio frequency signals to high-power signals. Its basic principle is to convert DC power into radio frequency energy.

[0072] The EH impedance matcher is a double-rail waveguide element. Adjusting the short-circuit pistons on the E and H planes changes the parameters of the waveguide element. Its main function is to change the load state of the microwave system, adjusting it to different states such as matched state, capacitive load, and inductive load. In the experiment, adjusting the impedance matcher to bring the system into a matched state improves the strength of the detected signal.

[0073] A waveguide direct-reading frequency meter is also installed between the detector and the straight waveguide. This frequency meter consists of a transmission waveguide, a cylindrical resonant cavity, and a direct-reading display mechanism. The cylindrical resonant cavity is excited using magnetic coupling through a rectangular aperture, and the piston in the resonant cavity is of an anti-current type. This waveguide direct-reading frequency meter is an absorption-type direct-reading frequency meter. When the resonant frequency of the cylindrical cavity of the frequency meter coincides with the microwave frequency of the waveguide being measured, a significant drop in transmission power can be observed from the indicator.

[0074] The detector is used to detect the envelope of a microwave signal, typically employing a square-law detector. The magnitude of the induced voltage reflects the microwave power intensity. When the microwave signal is a continuous wave, the output after detection is DC. The output signal is led out from the center conductor of a coaxial line connected to the detector and connected to a corresponding indicator, such as a DC meter or oscilloscope.

[0075] As a teaching platform for universities, it is necessary to ensure the safety of operation during the experiment. In university experimental instruments, the external power cords and the connection wires between other experimental instruments and equipment, or the electrical connection wires between equipment, are all properly insulated and wrapped. Acrylic plates are used to isolate and fix the electrode plates from the gas containers.

[0076] As a further improvement, the gas container is connected to the vacuum pump and the ammonia source via vacuum rubber tubing. Glass valves are also installed between the gas container and the vacuum pump, and between the gas container and the ammonia source. A needle valve is also installed between the gas container and the ammonia source. To ensure the airtightness of the device, all connections are coated with vacuum adhesive and sealing rubber, and a pressure gauge is provided to monitor the vacuum level of the square glass container in real time. The needle valve is used to control the gas flow rate.

[0077] As a further improvement, the output terminal of the detector is connected to a short-circuit piston, which is a single-arm microwave element connected to the terminal of the transmission system. The short-circuit piston reflects the incident microwave power without absorbing it, thereby forming a pure standing wave state in the transmission system.

[0078] As a further improvement, the exposed part of the alligator clip is wrapped with insulating tape, and the electrode plate is isolated and fixed to the square glass container with an acrylic plate.

[0079] As a further improvement, the short-circuit piston is a rectangular waveguide with a movable metal short-circuit surface. The position of the short-circuit surface of the short-circuit piston is adjusted by a screw and can be directly read.

[0080] As a further improvement, the frequency of the microwave signal output after amplification by the passive frequency multiplier is 22-26GHz, the applied electric field strength provided by the high voltage DC power supply is 10000-15000V / m, and the gas container is made of quartz or glass.

[0081] As a further improvement, the amplified output end of the horn antenna completely covers the side wall surface of the gas container.

[0082] The present invention also provides a method for using a teaching platform for measuring the inverted energy level of an ammonia molecule, applicable to any of the teaching platforms for measuring the inverted energy level of an ammonia molecule as described above.

[0083] Experimental principle:

[0084] Tests on the QM-VCO1113A voltage-controlled oscillator showed a linear relationship between the tuning voltage provided by the signal generator and the output frequency of the voltage-controlled oscillator in two ranges: 5-7V and 9.5-10.5V. Therefore, these two ranges were selected for verification of the corresponding relationship.

[0085] The molecule has a pyramidal shape, consisting of three hydrogen atoms forming a base plane, with a nitrogen atom at the top of this plane. Figure 4 As shown, the nitrogen atom is in a double potential well, with one potential well located on one side of the hydrogen atom plane and the other potential well located on the other side of the hydrogen atom plane. We call the nitrogen atom in the positive Z0 side the |1> state and the nitrogen atom in the negative Z0 side the |2> state.

[0086] From a quantum mechanical perspective, due to the quantum tunneling effect, a nitrogen atom on the hydrogen atom plane may tunnel to the other side of the hydrogen atom plane, thus forming two different states of ammonia molecules. The two different states of ammonia molecules tunnel through the tunneling potential well at different phases to form ammonia molecular quantum states, namely, a superposition of symmetric and antisymmetric states as follows:

[0087]

[0088] By symmetry, we can define:

[0089] H|1>=E0|1> H|2>=E0|2>

[0090] <2|H|1>=<1|H|2>=-A

[0091]

[0092] E=E0±A

[0093] Therefore, the inverted energy level of the nitrogen atom can be calculated:

[0094] ΔE0=|E - -E + |=24=hf J，K

[0095] Where A is the experimental constant to be measured, f J,K denoted as the reversal frequency of the nitrogen atom, and J and K are quantum numbers representing the rotational states of the ammonia molecule.

[0096] The rotational state of a molecule is determined by J and K, where J is the total angular momentum quantum number and K is the angular momentum quantum number along the z-axis. Based on current theoretical and experimental results, the ammonia molecule exhibits strong microwave absorption at J = 3, K = 3, and fo = 0. 3.3 ≈23.870GHz, another location is at J=6, K=6, f 6.6Since the ammonia molecule's absorption peak is approximately 25.056 GHz, we chose to measure the absorption peaks of the ammonia molecule near these two locations to verify its inverted energy level and further demonstrate the quantum tunneling effect of nitrogen atoms.

[0097] Example 1

[0098] The steps for measuring the (3,3) absorption peak include:

[0099] S1. Start the oscilloscope and warm it up for 20-40 minutes;

[0100] S2. Adjust the two horn antennas to ensure alignment;

[0101] S3. Place a gas container between the two horn antennas;

[0102] S4. Start the adjustable frequency microwave source and simultaneously adjust the operating voltage of the adjustable frequency microwave source to 5V;

[0103] S5. Adjust the voltage sequentially from small to large between 5.9-7.2V, while simultaneously measuring the microwave frequency with a frequency meter to obtain and record the relationship between the signal voltage V and the microwave frequency f(V).

[0104] S6. Turn on the vacuum pump and ammonia source, turn off the ammonia source after 8-12 minutes, and then turn off the vacuum pump after another 3-7 minutes. Observe and record the pressure value.

[0105] S7. Adjust the voltage sequentially from small to large between 6.1-6.9V, read and record the corresponding readings on the oscilloscope, and obtain the vacuum microwave signal spectrum I0(f);

[0106] S8. Turn on the ammonia source, observe and record the pressure reading, repeat S7, and obtain the ammonia microwave signal spectrum I1(f);

[0107] S9. Calculate the absorption spectrum α(f) of ammonia according to the formula, find the control voltage V and the corresponding frequency corresponding to the (3,3) absorption peak, compare it with the accurate measurement value of the (3,3) absorption peak and calculate the error.

[0108] The experimental data recorded according to the operating steps of Example 1 are shown in Table 1:

[0109] Table 1. Frequency-Control Voltage Values:

[0110]

[0111] This embodiment specifically involves measuring the absorption peak at 23.870 GHz.

[0112] Analysis results as follows Figure 5 As shown, according to Figure 5The fitting results show that the relationship between frequency and control voltage can be expressed as y = b + k*x, where x represents the control voltage in V, y represents the frequency in GHz, and the slope k is 0.419 GHz·V. -1 The intercept b is 21.144 GHz. Based on the correlation coefficient R... 2 It can be seen that the frequency and control voltage have a high degree of linear fit, almost a linear correlation, and this can be used as a basis for data collection.

[0113] Uncertainty analysis: Taking a control voltage of 5.90V as an example,

[0114]

[0115] (Take p = 0.683, t) vp =1.32)

[0116] Similarly, the remaining uncertainties can be derived.

[0117] Table 2. Voltage Values ​​- Control Voltage Values ​​(Air):

[0118]

[0119] Table 3. Voltage Values ​​- Control Voltage Values ​​(Ammonia):

[0120]

[0121]

[0122] Table 4. Absorption Rate - Control Voltage Values:

[0123] Control voltage (V) Absorption rate (%) 6.10 0.00 6.20 0.00 6.25 2.16 6.30 2.30 6.35 4.12 6.40 4.04 6.45 7.25 6.46 6.71 6.47 4.14 6.49 4.15 6.55 2.84 6.60 1.65 6.65 1.72 6.70 3.17 6.80 1.66 6.90 0.87

[0124] The formula for calculating absorption rate is:

[0125] like Figure 7 As shown, the experimentally measured absorption peak frequency is 23.858 GHz, and the theoretical value is 23.870 GHz. This is calculated using the relative error formula:

[0126] Relative error = |Measured value - Theoretical value| ÷ Theoretical value × 100%

[0127] =|23.858GHz-23.870GHz|÷23.870GHz×100%

[0128] =0.05%

[0129] The error is small, and the fit with the theoretical value is high.

[0130] Uncertainty analysis: Taking a control voltage of 6.10V (air) as an example,

[0131]

[0132] (Take p = 0.683, t) vp =1.32)

[0133] Similarly, the remaining uncertainties can be obtained, as detailed in the table.

[0134] Example 2

[0135] The steps for measuring the (6,6) absorption peak include:

[0136] S1. Start the oscilloscope and warm it up for 20-40 minutes;

[0137] S2. Adjust the two horn antennas to ensure alignment;

[0138] S3. Place a gas container between the two horn antennas;

[0139] S4. Start the adjustable frequency microwave source and simultaneously adjust the operating voltage of the adjustable frequency microwave source to 5V;

[0140] S5. Adjust the voltage from small to large between 9.1-10.0V, and at the same time use a frequency meter to measure the microwave frequency, obtain the relationship between the signal voltage V and the microwave frequency f(V) and record it.

[0141] S6. Turn on the vacuum pump and ammonia source, turn off the ammonia source after 8-12 minutes, and then turn off the vacuum pump after another 3-7 minutes. Observe and record the pressure value.

[0142] S7. Adjust the voltage sequentially from small to large between 9.2-10.3V, read and record the corresponding readings on the oscilloscope, and obtain the vacuum microwave signal spectrum I0(f);

[0143] S8. Turn on the ammonia source, observe and record the pressure reading, repeat S7, and obtain the ammonia microwave signal spectrum I1(f);

[0144] S9. Calculate the absorption spectrum α(f) of ammonia according to the formula, find the control voltage v and the corresponding frequency corresponding to the absorption peak (6,6), compare them with the accurate measurement value of the absorption peak (6,6), and calculate the error.

[0145] S10. Adjust the high voltage power supply to 5000V, the distance between the parallel plates is 7cm, and obtain the electric field strength. Repeat step S7 to obtain the microwave signal spectrum I1(f)' of ammonia under high voltage.

[0146] S11. Calculate the absorption spectrum α(f) of ammonia according to the formula, find the control voltage v and the corresponding frequency corresponding to the absorption peak (6,6), compare them with the accurate measurement value of the absorption peak (6,6), and calculate the error.

[0147] The experimental data recorded according to the operating steps of Example 2 are shown in Table 2:

[0148] Table 5. Frequency-Control Voltage Values:

[0149]

[0150]

[0151] This embodiment specifically involves measuring the absorption peak at 25.056 GHz.

[0152] Analysis results as follows Figure 6 As shown, according to Figure 6 The fitting results show that the relationship between frequency and control voltage can be expressed as y = b + k*x, where x represents the control voltage in V, y represents the frequency in GHz, and the slope k is 0.326 GHz·V. -1 The intercept b is 21.852 GHz. Based on the correlation coefficient R... 2 It can be seen that the frequency and control voltage have a high degree of linear fit, almost a linear correlation, and this can be used as a basis for data collection.

[0153] Uncertainty analysis: Taking a control voltage of 9.30V as an example,

[0154]

[0155] (Take p = 0.683, t) vp =1.32)

[0156] Similarly, the remaining uncertainties can be derived.

[0157] Table 6. Voltage Values ​​- Control Voltage Values ​​(Vacuum, 0.15 atm):

[0158]

[0159]

[0160] Table 7. Voltage Values ​​- Control Voltage Values ​​Table for Ammonia (0.66 atm):

[0161]

[0162] Table 8. Absorption Rate - Control Voltage Values:

[0163]

[0164]

[0165] The formula for calculating absorption rate is:

[0166] like Figure 8 As shown, the experimentally measured absorption peak frequency is 25.018 GHz, and the theoretical value is 25.056 GHz. This is calculated using the relative error formula:

[0167] Relative error = |Measured value - Theoretical value| ÷ Theoretical value × 100%

[0168] =|25.018GHz-25.056GHz|÷25.056GHz×100%

[0169] =0.05%

[0170] The error is small, and the fit with the theoretical value is high.

[0171] Uncertainty analysis: Taking a control voltage of 9.20V (air) as an example,

[0172]

[0173] (Take p = 0.683, t) vp =1.32)

[0174] Similarly, the remaining uncertainties can be obtained, as detailed in the table.

[0175] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A teaching platform for measuring the inverted energy level of ammonia molecules, characterized in that, include: Microwave module, gas module, measurement module, and pressurization module; The microwave module includes, A frequency-tunable microwave source is used to provide microwave signals required for experiments with a frequency of 11.0-13.0 GHz. The microwave signal is doubled by a passive frequency multiplier, wherein the frequency of the microwave signal output after amplification by the passive frequency multiplier is 22-26 GHz. A pair of symmetrically arranged EH impedance modulators are provided. The EH impedance modulators are connected to two horn antennas respectively through straight waveguides. The two horn antennas are symmetrically opposite each other and spaced apart. The EH impedance modulators are used to change the load state of the microwave system. The EH impedance modulators adjust the teaching platform system to a matched, capacitive load or inductive load state. The gas module includes, A gas container is disposed on one side of the output end of the frequency-tunable microwave source and between the two horn antennas. The gas container is externally connected to a vacuum pump and an ammonia source. The gas container forms a vacuum environment through the vacuum pump, and the ammonia source is used to replenish ammonia in the gas container after evacuation. The measurement module is located on the side of the gas module away from the microwave module. The measurement module includes a detector connected to the EH impedance tuner away from the frequency-tunable microwave source. The detector is externally connected to an oscilloscope. The detector couples the induced voltage between the two wide walls from the midpoint of the waveguide wide wall, and detects it through a microwave diode, so that the microwave signal is converted into a DC signal reflecting the microwave intensity. The pressurization module includes a high-voltage DC power supply, which is connected to a pair of electrode plates. The two electrode plates are respectively disposed on the upper and lower surfaces of the gas container. The high-voltage DC power supply is used to provide an external electric field to the ammonia gas in the evacuated gas container. The external electric field strength provided by the high-voltage DC power supply is 10000-15000V / m.

2. The teaching platform for measuring the inverted energy level of an ammonia molecule as described in claim 1, characterized in that, The gas container is connected to the vacuum pump and the ammonia source via vacuum rubber tubes. Glass valves are also provided between the gas container and the vacuum pump, and between the gas container and the ammonia source. A needle valve is also provided between the gas container and the ammonia source.

3. The teaching platform for measuring the inverted energy level of an ammonia molecule as described in claim 1, characterized in that, The output terminal of the detector is connected to a short-circuit piston, which is a single-arm microwave element connected to the terminal of the transmission system. The short-circuit piston reflects the incident microwave power without absorbing it, thus forming a pure standing wave state in the transmission system.

4. The teaching platform for measuring the inverted energy level of an ammonia molecule as described in claim 3, characterized in that, The short-circuit piston is a rectangular waveguide with a movable metal short surface. The position of the short surface of the short-circuit piston is adjusted by a screw and can be directly read.

5. The teaching platform for measuring the inverted energy level of an ammonia molecule as described in claim 1, characterized in that, The gas container is made of quartz or glass.

6. The teaching platform for measuring the inverted energy level of an ammonia molecule as described in claim 1, characterized in that, The amplified output end of the horn antenna completely covers the side wall surface of the gas container.

7. A method for using a teaching platform for measuring the inverted energy level of an ammonia molecule, characterized in that, A teaching platform for measuring the inverted energy level of an ammonia molecule as described in any one of claims 1-6, used to measure the absorption peak corresponding to the J=3, K=3 inverted energy level of an ammonia molecule, where J is the total angular momentum quantum number and K is the angular momentum quantum number along the z-axis, includes the following steps: S1. Start the oscilloscope and warm it up for 20-40 minutes; S2. Adjust the two horn antennas to ensure alignment; S3. Place a gas container between the two horn antennas; S4. Start the adjustable frequency microwave source and simultaneously adjust the operating voltage of the adjustable frequency microwave source to 5V; S5. Adjust the voltage sequentially from low to high between 5.9-7.2V, while simultaneously measuring the microwave frequency with a frequency counter to obtain the signal voltage. V With microwave frequency Record the relationships between them; S6. Turn on the vacuum pump and ammonia source, turn off the ammonia source after 8-12 minutes, and then turn off the vacuum pump after another 3-7 minutes. Observe and record the pressure value. S7. Adjust the voltage sequentially from low to high within the range of 6.1-6.9V, and read and record the corresponding readings on the oscilloscope to obtain the vacuum microwave signal spectrum. ; S8. Turn on the ammonia gas source, observe and record the pressure reading, repeat S7, and obtain the ammonia microwave signal spectrum. ; S9. Calculate the absorption spectrum of ammonia gas according to the formula. Find the control voltage corresponding to the absorption peak of the inverted energy level of the ammonia molecule when J=3 and K=3. V The corresponding frequencies are compared with the precise measured values ​​of the absorption peaks corresponding to the J=3, K=3 inverted energy levels of the ammonia molecule, and the error is calculated.

8. A method for using a teaching platform for measuring the inverted energy level of an ammonia molecule, characterized in that, A teaching platform for measuring the inverted energy level of an ammonia molecule as described in any one of claims 1-6, used to measure the absorption peak corresponding to the J=6, K=6 inverted energy level of an ammonia molecule, where J is the total angular momentum quantum number and K is the angular momentum quantum number along the z-axis, includes the following steps: S1. Start the oscilloscope and warm it up for 20-40 minutes; S2. Adjust the two horn antennas to ensure alignment; S3. Place a gas container between the two horn antennas; S4. Start the adjustable frequency microwave source and simultaneously adjust the operating voltage of the adjustable frequency microwave source to 5V; S5. Adjust the voltage sequentially from low to high between 9.1-10.0V, while simultaneously measuring the microwave frequency with a frequency counter to obtain the signal voltage. V With microwave frequency Record the relationships between them; S6. Turn on the vacuum pump and ammonia source, turn off the ammonia source after 8-12 minutes, and then turn off the vacuum pump after another 3-7 minutes. Observe and record the pressure value. S7. Adjust the voltage sequentially from low to high within the range of 9.2-10.3V, and record the corresponding readings on the oscilloscope to obtain the vacuum microwave signal spectrum. ; S8. Turn on the ammonia gas source, observe and record the pressure reading, repeat S7, and obtain the ammonia microwave signal spectrum. ; S9. Calculate the absorption spectrum of ammonia gas according to the formula. Find the control voltage corresponding to the absorption peak of the inverted energy level of the ammonia molecule at J=6 and K=6. V And compare the corresponding frequencies with the precise measured values ​​of the absorption peaks corresponding to the J=6, K=6 inverted energy levels of the ammonia molecule and calculate the error; S10. Adjust the high-voltage power supply to 5000V, with the spacing between the parallel plates at 7cm, and obtain the electric field strength. Repeat step S7 to obtain the microwave signal spectrum of ammonia gas under high voltage. '; S11. Calculate the absorption spectrum of ammonia gas according to the formula. Find the control voltage V and the corresponding frequency of the absorption peak corresponding to the J=6, K=6 inverted energy level of the ammonia molecule, compare it with the accurate measurement value of the absorption peak corresponding to the J=6, K=6 inverted energy level of the ammonia molecule, and calculate the error.

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