CN1278119C - Detection device and detection method for radio frequency resonance absorption signal of linear ion trap - Google Patents

Abstract

The invention discloses a detection device and a detection method of a linear ion trap radio frequency resonance absorption signal and relates to atomic and molecular physics. The device consists of a homologous signal generator (1), a radio frequency power amplifier (2), a lock-in amplifier (3), a computer (4), a trapping field step-up transformer (5), a linear ion trap (6), and a grounding point (7), coupling capacitor (8) is formed; Replace the narrow-band amplifier of existing this detection device with lock-in amplifier, separate the signal of three homologous different frequencies with same source signal, its advantage is: make full use of lock-in amplifier The phase amplifier features high precision, high sensitivity, high Q value, and good selectivity; it solves the synchronization problem between the external reference channel and the signal channel of the lock-in amplifier, and effectively improves the sensitivity of the detection system. Technology is at least an order of magnitude higher.

Description

The pick-up unit and the detection method of linear ion trap radioresonance absorption signal

Technical field:

The present invention relates to atomic and molecular physics, more specifically relate to the detection of ion trap radioresonance absorption signal.

Background technology:

Ion trap can be stored ion for a long time, can obtain a kind of isolated ionic system that is close to, and creates a kind of " free space " of cleaning for the ion that is studied.For foundation of physics research provides desirable research object.In the applied research field, extensively had an optimistic view of as the prospect of high precision of new generation, high stability ion frequency marking.Therefore ion imprison technology in the ion trap physics and relevant experimental technique and acquisition of signal means are one of important component parts in the experiment.

The detection of trapped ion signal has several different methods, and wherein the radioresonance absorption detecting more easily realizes.Its principle is: the ion of imprison in trap is with certain specific frequency movement, add a faint checkout area outside in the testing circuit, the energy that the ion of imprison in trap will the absorption detecting field when the frequency of checkout area equates with the micromotion frequency of ion, the amplitude of checkout area will descend, and forms an absorption peak.The peak height of absorption peak is relevant with the sensitivity of the population of ions of imprison in trap and testing circuit.When the parameters such as working point of trap body determine the sensitivity of back detection system high more can detected ion populations with regard to few more be that signal to noise ratio (S/N ratio) is high more.

The pick-up unit of radioresonance absorption signal is made up of 500 KHz imprison field, 50 KHz narrow-band amplifiers, computing machine, imprison field step-up transformer, linear ion trap, earth point, coupling capacitance C in the existing linear ion trap.Radio-frequency signal generator produces high-frequency electric field that 500 KHz signals convert 500 volts ion trap trapped ion to through high-frequency transformer and receives and be used for imprisoning selecteed ion in the linear ion trap.The sine wave signal of 550 KHz is through the center winding of coupling capacitance to high-frequency transformer.Another center tap of high-frequency transformer is connected to earth point.Scan the voltage amplitude of imprisoning the field by the ion that is trapped in the trap by computer control in the experiment, will detect the signal of 50 KHz at the hub of a spool tapping point that is connected to 50 KHz narrow-band amplifiers.This signal is 50 KHz from the difference frequency of 550 KHz checkout areas and 500 KHz imprison field.Amplified by narrow-band amplifier, computing machine is gathered the signal from amplifier in scanning again.And demonstration mapping.The weak point of this pick-up unit is: the detection of signal is asynchronous with imprison, detection sensitivity is low, poor signal to noise, detected signal amplitude are little.

Different frequency is with the exportable 500 KHz square-wave signals of source signal generator, 550 KHz sine wave signals and 50 KHz square-wave signals.

Summary of the invention:

The objective of the invention is, a kind of pick-up unit of linear ion trap radioresonance absorption signal is provided, this device replaces the narrow-band amplifier of existing this pick-up unit with lock-in amplifier, told the signal of three homology different frequencies with same oscillation source signal, solved the stationary problem between lock-in amplifier External Reference passage and the signalling channel, the sensitivity that has improved detection system effectively.

Another object of the present invention is that a kind of detection method of linear ion trap radioresonance absorption signal is provided.

In order to achieve the above object, the present invention adopts following technical scheme:

A kind of pick-up unit of linear ion trap radioresonance absorption signal, this device is made up of same source signal generator, radio-frequency power amplifier, lock-in amplifier, computing machine, imprison field step-up transformer, linear ion trap, earth point, coupling capacitance.Export three road signals with source signal generator, first via signal be 500 KHz square-wave signals to radio-frequency power amplifier, the second road signal be the sine wave signal of 550 KHz to coupling capacitance, the Third Road signal is that 50 KHz square waves are to lock-in amplifier; Radio-frequency power amplifier zooms into sine wave signal with the first via signal that receives, and controls its output amplitude by computer scanning simultaneously; An imprison step-up transformer will become the high-frequency electric field of 500 volts ion trap trapped ion from the conversion of signals of power amplifier; Coupling capacitance outputs to the weak checkout area of the central point of the detection winding of imprisoning a step-up transformer as resonance absorption with the sine wave signal of the second tunnel 550 KHz; The signal of lock-in amplifier is imported from the output terminal of coupling capacitance and synchronous with Third Road 50 KHz square-wave signals; Signal after the amplification is to computing machine; Computing machine produces the one scan signal simultaneously and causes radio-frequency power amplifier and control its output amplitude; Linear ion trap is used for imprisoning selecteed ion.

The method that detects the radioresonance absorption signal of linear ion trap trapped ion with the pick-up unit of linear ion trap radioresonance absorption signal of the present invention follows these steps to carry out:

1, in linear ion trap,, produces and treat measured ion with electron gun bombarding gas atom;

2, export the pulse signal of 500 KHz, 550 KHz and 50 KHz, three road different frequencies with source signal generator;

3,500 KHz square-wave signals become sinusoidal wave through radio-frequency power amplifier, become radio-frequency voltage by step-up transformer again, and linear ion trap is under the effect of radio-frequency voltage, treating that the measured ion imprison is in linear ion trap;

4, close electron gun;

5,550 KHz sine wave signals output to the central point of the detection winding of imprisoning a step-up transformer as weak checkout area through coupling capacitance;

6,50 KHz square-wave signals are made the External Reference signal to lock-in amplifier;

7, computing machine evenly is divided into the 10-100 analog voltage with the aanalogvoltage of 0-5 volt, export aanalogvoltage one by one to radio-frequency power amplifier, radio-frequency power amplifier becomes radio-frequency voltage by step-up transformer again with the aanalogvoltage and the common synthesis sine of 500 KHz square-wave signals of computing machine output;

8, the relation of radio-frequency voltage value and ion micromotion frequency is determined by following formula:

${\mathrm{\&omega;}}^2=\frac{q^2{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="C20031011160300121.png"\; state="\{\{state\}\}">V</figure-callout>}}^2}{2{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="C20031011160300121.png"\; state="\{\{state\}\}">m</figure-callout>}}^2{\mathrm{\&Omega;}}^2{\mathrm{<figure-callout\; id="4"\; label="R"\; filenames="C20031011160300121.png"\; state="\{\{state\}\}">R</figure-callout>}}^4}$

ω is the micromotion angular frequency of imprison at the trap intermediate ion;

Q is an electronic charge;

V is the voltage of imprison field;

Ω is the angular frequency of imprison field;

M is the quality of ion of being held in captivity;

R is the physical dimension of ion trap.

Just in time the micromotion angular frequency with ion is corresponding as radio-frequency voltage value V, and the weak checkout area frequency of this frequency and step 5 is when identical, the ion of imprison in the line style trap can absorb the energy of outside weak checkout area, lock-in amplifier can detect an absorption peak, peak value is exactly the micromotion frequency of trapped ion, the radioresonance absorption signal of Here it is linear ion trap trapped ion.

The present invention's advantage compared with prior art is: replace narrow-band amplifier with lock-in amplifier, make full use of the high precision, high sensitivity, high Q value of lock-in amplifier, the characteristics that selectivity is good; Told the signal of three homology different frequencies with same oscillation source signal, solved the stationary problem between lock-in amplifier External Reference passage and the signalling channel, improved the sensitivity of detection system effectively, its remolding sensitivity prior art exceeds an order of magnitude at least.

Description of drawings:

Fig. 1 is a structural representation of the present invention.

Wherein: 1 is that same source signal generator, 2 is that radio-frequency power amplifier, 3 is that lock-in amplifier, 4 is that computing machine, 5 is that step-up transformer, 6 is that linear ion trap, 7 is that earth point, 8 is a coupling capacitance.

Embodiment:

The present invention is further illustrated below in conjunction with accompanying drawing:

As shown in Figure 1: the pick-up unit of a kind of linear ion trap radioresonance absorption signal of the present invention is by forming with source signal generator 1, radio-frequency power amplifier 2, lock-in amplifier 3, computing machine 4, an imprison step-up transformer 5, linear ion trap 6, earth point 7, coupling capacitance 8.With source signal generator 1 output three road signals, first via signal is that 500 KHz square-wave signals are to radio-frequency power amplifier 2, the second road signal is that the sine wave signal of 550 KHz arrives coupling capacitance 8, the Third Road signal is that 50 KHz square waves are to lock-in amplifier 3, as the External Reference input of lock-in amplifier 3; Radio-frequency power amplifier 2 zooms into sine wave signal with the first via signal that receives, its output amplitude of simultaneous computer 4 scan control; An imprison step-up transformer 5 will become the high-frequency electric field of 500 volts ion trap trapped ion from the conversion of signals of power amplifier 2; Coupling capacitance 8 adopts 1000 picofarads that the sine wave signal of the second tunnel 550 KHz is outputed to the central point of the detection winding of an imprison step-up transformer 5, is connected to the weak checkout area of linear ion trap as resonance absorption; The signal input of lock-in amplifier 3 is from the output terminal of coupling capacitance 8, and the signal after lock-in amplifier 3 amplifies is to computing machine 4.Computing machine 4 produces the one scan signal simultaneously to radio-frequency power amplifier 2 its output amplitudes of control.Linear ion trap 6 is used for imprisoning selecteed ion.The sine wave signal of 550 KHz outputs to the detection winding of imprisoning a step-up transformer 5 through the coupling capacitance of 1000 picofarads, as weak checkout area.

The method that detects the radioresonance absorption signal of linear ion trap trapped ion with the pick-up unit of linear ion trap radioresonance absorption signal of the present invention follows these steps to carry out:

1, in linear ion trap 6,, produces and treat measured ion with electron gun bombarding gas atom;

2, export the pulse signal of 500 KHz, 550 KHz and 50 KHz, three road different frequencies with source signal generator 1;

3,500 KHz square-wave signals are sinusoidal wave through 2 one-tenth of radio-frequency power amplifiers, and again by 5 one-tenth radio frequency high tensions of step-up transformer, linear ion trap 6 is under the effect of radio frequency high tension, treating that the measured ion imprison is in linear ion trap 6;

4, close electron gun;

5,550 KHz sine wave signals output to the central point of the detection winding of imprisoning a step-up transformer 5 as weak checkout area through coupling capacitance 8;

6,50 KHz square-wave signals are made the External Reference signal to lock-in amplifier 3;

7, computing machine 4 evenly is divided into the 10-100 analog voltage with the aanalogvoltage of 0-5 volt, export aanalogvoltage one by one to radio-frequency power amplifier 2, radio-frequency power amplifier 2 is with the aanalogvoltage and the common synthesis sine of 500 KHz square-wave signals of computing machine output, again by 5 one-tenth radio-frequency voltages of step-up transformer;

8, the relation of radio-frequency voltage value and ion micromotion frequency is determined by following formula:

${\mathrm{\&omega;}}^2=\frac{q^2{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="C20031011160300121.png"\; state="\{\{state\}\}">V</figure-callout>}}^2}{2{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="C20031011160300121.png"\; state="\{\{state\}\}">m</figure-callout>}}^2{\mathrm{\&Omega;}}^2{\mathrm{<figure-callout\; id="4"\; label="R"\; filenames="C20031011160300121.png"\; state="\{\{state\}\}">R</figure-callout>}}^4}$

ω is the micromotion angular frequency of imprison at the trap intermediate ion;

Q is an electronic charge;

V is the voltage of imprison field;

Ω is the angular frequency of imprison field;

M is the quality of ion of being held in captivity;

R is the physical dimension of ion trap.

When radio-frequency voltage value V just in time corresponding with ion micromotion angular frequency, and the weak checkout area frequency of this frequency and step 5 is when identical, the ion of imprison in linear ion trap 6 can absorb the energy of outside weak checkout area, lock-in amplifier 3 can detect an absorption peak, peak value is exactly the micromotion frequency of trapped ion, the radioresonance absorption signal of Here it is linear ion trap trapped ion.

Claims (2)

1. The detection device of linear ion trap radio frequency resonance absorption signal is characterized in that the device consists of homologous signal generator (1), radio frequency power amplifier (2), lock-in amplifier (3), computer (4), imprisoned Composed of field step-up transformer (5), linear ion trap (6), grounding point (7), and coupling capacitor (8); homologous signal generator (1) outputs three signals, the first signal is 500 kHz The square wave signal goes to the radio frequency power amplifier (2), the sine wave signal of the second road signal is 550 kilohertz to the coupling capacitor (8), and the third road signal is a 50 kilohertz square wave to the lock-in amplifier (3); the radio frequency power The amplifier (2) amplifies the received first signal into a sine wave signal, and the computer (4) scans and controls its output amplitude; the prison field step-up transformer (5) converts the signal from the power amplifier (2) into a 500 The high-frequency electric field that the ion trap of volts imprisons ions; Coupling capacitance (8) outputs the sine wave signal of the second road 550 kilohertz to the central point of the detection winding of imprisoned field step-up transformer (5), and imprisoned field step-up transformer ( 5) connected to the linear ion trap (6), the linear ion trap (6) is used to imprison the selected ions; the signal input of the lock-in amplifier (3) comes from the output terminal of the coupling capacitor (8), and is connected with the third The 50 kilohertz square wave signal of the road is synchronized; the amplified signal is sent to the computer (4); the computer (4) simultaneously generates a scanning signal to the radio frequency power amplifier (2) to control its output amplitude. 2. The method for detecting the radio frequency resonance absorption signal of the linear ion trap trapped ion with the detection device of the linear ion trap radio frequency resonance absorption signal according to claim 1 is carried out according to the following steps: a. In the linear ion trap (6), bombard the gas atoms with an electron gun to generate ions to be measured; B, homologous signal generator (1) outputs the pulse signal of three different frequencies of 500 kilohertz, 550 kilohertz and 50 kilohertz; c. The 500 kHz square wave signal becomes a sine wave through the radio frequency power amplifier (2), and then becomes a radio frequency voltage by a step-up transformer (5). The linear ion trap (6) traps the ions to be measured under the action of the radio frequency voltage In the linear ion trap (6); d. Turn off the electron gun; E, 550 kilohertz sine wave signal is exported to the central point of the detection winding of imprisoned field step-up transformer (5) through coupling capacitor (8) as weak detection field; F, 50 kilohertz square wave signal to lock-in amplifier (3), make external reference signal; G, computer (4) divides the analog voltage of 0-5 volts into 10-100 analog voltage values evenly, output analog voltage to radio frequency power amplifier (2) one by one, radio frequency power amplifier (2) the analog voltage of computer output and 500 thousand The hertzian square wave signals are jointly synthesized into a sine wave, which is then converted into a radio frequency voltage by a step-up transformer (5); h. The relationship between the radio frequency voltage value and the ion micro-motion frequency is determined by the following formula: ${\mathrm{\&omega;}}^2=\frac{q^2{V}^2}{2m^2{\mathrm{\&Omega;}}^2{R}^4}$ ω is the micromotion angular frequency of ions trapped in the trap; q is the electronic charge; V is the voltage of the trapping field; Ω is the angular frequency of the trapping field; m is the mass of the trapped ion; R is the geometric size of the ion trap; When the radio frequency voltage value V just corresponds to the ion micro-motion angular frequency ω, and this frequency is the same as the frequency of the weak detection field in step e, the ions trapped in the linear ion trap (6) will absorb the energy of the external weak detection field, locking The phase amplifier (3) will detect an absorption peak, which is the micro-motion frequency of the trapped ions, which is the radio frequency resonance absorption signal of the trapped ions in the linear ion trap.

Images