CN102830381B - Nuclear magnetic resonance (NMR) device and measurement method based on laser atomic magnetometer - Google Patents
Nuclear magnetic resonance (NMR) device and measurement method based on laser atomic magnetometer Download PDFInfo
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Abstract
The invention discloses a nuclear magnetic resonance (NMR) device based on a laser atomic magnetometer, and the NMR device comprises a cesium atom vapor bubble, a magnetic shielding bushing which is sleeved on the cesium atom vapor bubble, three groups of Helmholtz coils which are arranged inside the magnetic shielding bushing, a polarization device which is used for polarizing cesium atoms inside the cesium atom vapor bubble, a laser transmitting device which is used for transmitting detection laser to the cesium atom vapor bubble, a detection device which is used for detecting an NMR signal of the detection laser penetrating the cesium atom vapor bubble and a pneumatic sample feeding device which is used for pre-polarizing a sample to be detected and can place the pre-polarized sample on the cesium atom vapor bubble. The invention also discloses a measurement method of an NMR based on the laser atomic magnetometer. The device and the method are high in detection sensitivity, free from needing low-temperature refrigeration, low in running cost and lower in working temperature.
Description
Technical field
The invention belongs to nuclear magnetic resonance (Nuclear magnetic resonance, NMR) spectrum, more specifically relate to a kind of NMR device based on laser atomic magnetic force meter, also relate to the measuring method of a kind of NMR based on laser atomic magnetic force meter, be applicable to (the 1uT=10 at 100uT～1nT
-6t, 1nT=10
-9t) under magnetic field, detect NMR signal.
Background technology
NMR is a kind of be used for the obtaining molecular structure that forms about atom and atom and technology of dynamic information.NMR works to atomic nucleus, and only the atomic nucleus with non-vanishing spin is worked, and these non-vanishing nuclear spins, just as having one by one the small magnet of south poles, have magnetic moment, thereby can be used to NMR research.
In the time that these magnetic moments are in outside static magnetic field, owing to there is angle in magnetic moment and outer static magnetic field, because generation precession, when using radio-frequency (RF) magnetic field irradiated atoms core, atomic nucleus absorbs radio-frequency (RF) energy, and launch the radiofrequency signal corresponding with precession speed, the characteristic information that this radiofrequency signal can reaction of atomic core.Atomic nucleus is in certain environment, there is interaction in various degree in these environment and atomic nucleus, be reflected in the radiofrequency signal emitting, can cause it in strength, to have relaxation phenomenon, by studying this attenuate action, can obtain the circumnuclear space structure of atom and dynamic behaviour information.
In NMR wave spectrum, change the frequency of radio-frequency (RF) magnetic field, measure absorption and the emissive porwer of atomic nucleus to different frequency radio-frequency (RF) magnetic field, can obtain resonance spectrum, this NMR wave spectrum can disclose elemental composition and the content of material, be combined with correlation theory, even can obtain structure and the movable information of each element atom.
NMR invented before and after the 1950's, in the developing history of its decades, for obtaining higher NMR spectral resolution, magnetic field intensity and radio-frequency (RF) field frequency are increasing always, from Larmor (Larmor) frequency of initial 10MHz magnitude, 900MHz up till now, even has the NMR spectrometer of producer at development GHz radio-frequency field.
Although High-Field NMR has high resolving power, from practical application, high field intensity and high RF frequency are restricted in some application.Along with the raising in magnetic field, the unevenness that magnetic sample conductance distributes can be aggravated, thereby makes signal broadening, and the sample that especially comprises the ferromagnetic elements such as iron-cobalt-nickel, normally cannot analyze by NMR technology.Another FAQs is the magnetic susceptibility artifact in magnetic resonance imaging (Magnetic resonance imaging, MRI).In the time that variety classes sample or the similar sample with higher susceptibility gradient are in magnetic field, the sample composition of different magnetic susceptibility can produce parasitic gradient magnetic.When these parasitic gradient fields are when suitable for the gradient fields of encoding, the image serious distortion of MRI.In medical imaging, the existence of metal dental filling or jewellry can destroy MRI; The saltus step of body interior solid-liquid and solid-air interface place magnetic susceptibility, produces trickle distortion.
From scientific research, conventionally the true environment of chemical example and biological tissue is terrestrial magnetic field (40～50uT), for obtaining as far as possible point subsample and tissue structure and the dynamic information under actual environment, need to be used in the original position research of carrying out NMR and MRI under low (terrestrial magnetic field and following) condition; But traditional RF coil Detection Techniques, because it is in low muting sensitivity after the match, have some limitations in the time carrying out this type of research.
Although based superconductive quantum interference device (Superconducting quantum interference device, SQUID) magnetometer, also can be in the very high detection of magnetic field sensitivity of low realization after the match, and be applied to low NMR research, but it is the same with NMR spectrometer, be operated in the required low temperature environment of superconduction, still limit to some extent in application aspect.
In sum, although NMR is applied widely in each field as a kind of powerful nuclear spin analytical technology, but NMR technology RF used (Radio Frequency) coil is poor in low detection sensitivity after the match at present, still can not meet the requirement of some application.
Therefore, we need some low high sensitivity NMR instrument and technology after the match.Development in recent years has gone out several low NMR instruments, and these technology have made up traditional NMR in low muting sensitivity defect after the match.The people such as I.M.Savukov are at " NMR Detection with an Atomic Magnetometer " (Phys.Rev.Lett.94,123001 (2005)) in, carry out NMR detection with laser atomic magnetic force meter, this laser atomic magnetic force meter uses in potassium (K) atom of 180 DEG C as actuating medium, has 20fT/Hz at direct current on the frequency range of hundreds of Hz
1/2sensitivity, record the NMR signal of water taking signal to noise ratio (S/N ratio) (Signal to noise ratio, SNR) as 10 unitary sampling.The people such as V.V.Yashchuk in " Hyperpolarized Xenon Nuclear Spins Detected by Optical Atomic Magnetometry " (Phys.Rev.Lett.93,160801 (2004)) by atomic magnetic force instrumentation amount the T of hyperpolarization Xe atom
1constant.The C-H J coupling spectrum (one of NMR spectrum of ethanol that the people such as M.P.Ledbetter have used laser atomic magnetic force instrumentation amount in " Optical detection of NMR J-spectra at zero magnetic field ", can be used for determining the structure in chemical molecular), and this measurement is carried out under zero magnetic field.
The one of laser atomic magnetic force meter based on atom and laser interaction generation is called as the quantum-mechanical phenomenon of non-linear magneto-optical rotation (Nonlinear magneto-optical rotation, NMOR).The NMOR signal producing due to this phenomenon has extremely narrow live width, and to magnetic-field-sensitive, and therefore natural have a highly sensitive magnetic field detection ability, and in addition, even under Exceedingly feeble magnetic field as even lower in 100uT～1nT magnitude, this sensitivity can variation yet.
The above-mentioned method of utilizing laser atomic magnetic force meter to detect NMR signal, also has certain defect, such as the probe of laser atomic magnetic force meter is an atomic vapour bubble that works in 170～210 DEG C of left and right, its excess Temperature, NMR sample is had to the impact of spectral line broadening, the present invention will be for this problem, proposes a kind of new method.
Summary of the invention
The object of the invention is to be the problems referred to above for prior art existence, a kind of NMR device based on laser atomic magnetic force meter is provided, the measuring method of a kind of NMR based on laser atomic magnetic force meter is also provided, thereby solve low existing radio-frequency coil method under-sensitive difficulty after the match, and solve the problem of emerging atomic vapour bubble excess Temperature.
To achieve these goals, the present invention is by the following technical solutions:
A kind of NMR device based on laser atomic magnetic force meter, comprise caesium atomic vapour bubble, comprise the magnetic shielding sleeve being set on caesium atomic vapour bubble, be arranged on three groups of Helmholtz coilss in magnetic shielding sleeve, for the laser-polarization device of caesium atom in the caesium atomic vapour bubble that polarizes, for the laser beam emitting device to caesium atomic vapour bubble emission detection laser, for detection of the NMR signal supervisory instrument of the exploring laser light through caesium atomic vapour bubble with for sample being carried out to the pre-pneumatic sample-feeding device that polarizes and the sample after polarizing in advance can be placed into caesium atomic vapour bubble top.
Laser-polarization device as above comprises optically pumped laser and is converted to the quarter-wave plate that is sent to caesium atomic vapour bubble after circularly polarized light for the laser that optically pumped laser is sent.
Laser beam emitting device as above comprises detecting laser and converts the polarizing prism that is sent to caesium atomic vapour bubble after linear polarization exploring laser light for the laser that detecting laser is sent to.
NMR signal supervisory instrument as above comprises the polarization beam splitter prism for the linear polarization exploring laser light that passes caesium atomic vapour bubble is carried out to beam splitting, for detection of the linear polarization exploring laser light after beam splitting and detection signal is sent to the photodetector of multiplier, for adjusting the output frequency of optically pumped laser and exporting the signal generator of square wave synchronizing signal to multiplier, for detection signal and square wave synchronizing signal being carried out to the multiplier of multiplying and for the output of multiplier being carried out to filtering and being sent to the low-pass filter of host computer.
Pneumatic sample-feeding device as above comprises cylinder, be arranged in cylinder and one end is provided with the sample hose of the piston of cylinder inner wall laminating, is set in the pre-polarized magnets of annular of cylinder one end and for Quality control pipe reciprocating drive unit in cylinder, on described magnetic shielding sleeve, offer through hole, cylinder one end is arranged on caesium atomic vapour bubble top through through hole.
Cylinder as above one end is arranged with guiding coil, and the other end is arranged with low-angle pulsed coil, and described drive unit comprises the solenoid valve that the air compressor of pneumatic supply is provided and is input to the airflow direction of cylinder for switching air compressor.
Three groups of Helmholtz coilss as above comprise three pairs of annular Helmholtz coilss, the center line of every pair of Helmholtz coils overlaps, the center line of three pairs of Helmholtz coilss is mutually vertical, and wherein the center line of a pair of Helmholtz coils and the beam direction of exploring laser light are parallel.
A measuring method of NMR based on laser atomic magnetic force meter, comprises the following steps:
Step 1, control caesium atomic vapour bubble temperature rise to 20-60 DEG C, control Output of laser frequency and the resonance of alkaline metal caesium atom D1 line transition F=4->F '=3 of optically pumped laser, and control this resonant frequency of Output of laser frequency departure 100MHz～100GHz of detecting laser, electric current to optically pumped laser is modulated, and realizes synchronizable optical pumping;
The angle of step 2, adjustment polarizing prism and quarter-wave plate, obtains linear polarization exploring laser light and circularly polarized light;
The angle of step 3, adjustment polarization beam splitter prism, until the signal of photodetector output is zero;
Step 4, by adjusting the electric current of three groups of Helmholtz coilss, make residual magnetic field in magnetic shielding sleeve for minimum, obtain the adjustment electric current of three groups of Helmholtz coilss;
Electric current in step 5, the center line of scanning in the three groups of Helmholtz coilss a pair of Helmholtz coils parallel with exploring laser light, the positive current values equating with the negative current magnitude of setting from negative current magnitude to absolute value of setting, be superimposed upon on the adjustment electric current described in step 4, obtain the magnetic field distinguishing signal of low-pass filter output;
Step 6, repeating step 2～step 5 be until when unit changes of magnetic field, the changing value maximum of low-pass filter output voltage response, and the B value of setting range of linearity center, magnetic field is bias magnetic field;
Step 7, get appropriate amount of fluid sample and pour sample hose into, put into cylinder;
Step 8, host computer be by Control solenoid valve, and then control air compressor and be blown into the direction in cylinder, and sample hose is floated to the inside center of the pre-polarized magnets of annular;
Step 9, keep sample hose suspension setting-up time, make its fully pre-polarization, host computer is by Control solenoid valve, and then changes air compressor and be blown into the direction in cylinder, makes sample hose be passed down through guiding coil, arrives the top of caesium atomic vapour bubble;
Electric current in step 10, control low-angle pulsed coil, produces direct current or alternating-current pulse, changes sample magnetic moment direction;
There is the little angle of 5～15 degree in the direction of step 11, sample magnetic moment and bias magnetic field, sample magnetic moment is subject to physically the effect of a moment and does precession around bias magnetic field, and magnetic field is applied to disturbance, obtains the NMR signal of time domain;
The NMR spectrum signal of step 12, NMR signal acquisition frequency field by time domain.
The present invention compared with prior art, has the following advantages and effect:
1,, under downfield, compared with existing coil Detection Techniques, there is higher detection sensitivity;
2, compared with utilizing SQUID detection NMR technology with existing low field, do not need cryogenic refrigeration, save operating cost;
3, compared with the existing NMR sniffer based on atomic magnetic force meter, there is lower working temperature.
Brief description of the drawings
Fig. 1 is general structure schematic diagram of the present invention;
Fig. 2 is the principle schematic of high sensitivity laser atomic magnetic force of the present invention test section;
Fig. 3 is the principle schematic of pre-polarization of the present invention and gas driven injection part.
In figure: 1-detecting laser; 2-optically pumped laser; 3-polarizing prism; 4-quarter-wave plate; 5-magnetic shielding sleeve; Tri-groups of Helmholtz coilss of 6-; 7-caesium atomic vapour bubble; 8-polarization beam splitter prism; 9-photodetector; 10-multiplier; 11-signal generator; 12-low-pass filter; 13-host computer; 14-air compressor; 15-solenoid valve; 16-relay; 17-sample hose; 18-cylinder; The pre-polarized magnets of 19-annular; 20-guides coil; 21-low-angle pulsed coil; The pre-polarization of a-sample and pneumatic sample-feeding device; B-laser atomic magnetic force counter device.
Embodiment
Below in conjunction with accompanying drawing, the present invention is described in further detail:
Embodiment:
A kind of NMR device based on laser atomic magnetic force meter, comprise caesium atomic vapour bubble 7, comprise the magnetic shielding sleeve 5 being set on caesium atomic vapour bubble 7, be arranged on three groups of Helmholtz coilss 6 in magnetic shielding sleeve 5, for the laser-polarization device of the interior caesium atom of caesium atomic vapour bubble 7 that polarizes, for the laser beam emitting device to caesium atomic vapour bubble 7 emission detection laser, for detection of the NMR signal supervisory instrument of the exploring laser light through caesium atomic vapour bubble 7 with for sample being carried out to the pre-pneumatic sample-feeding device that polarizes and the sample after polarizing in advance can be placed into caesium atomic vapour bubble 7 tops.
Laser-polarization device comprises optically pumped laser 2 and is converted to the quarter-wave plate 4 that is sent to caesium atomic vapour bubble 7 after circularly polarized light for the laser that optically pumped laser 2 is sent.
Laser beam emitting device comprises detecting laser 1 and converts the polarizing prism 3 that is sent to caesium atomic vapour bubble 7 after linear polarization exploring laser light for the laser that detecting laser 1 is sent to.
NMR signal supervisory instrument comprises the polarization beam splitter prism 8 for the linear polarization exploring laser light that passes caesium atomic vapour bubble 7 is carried out to beam splitting, for detection of the linear polarization exploring laser light after beam splitting and detection signal is sent to the photodetector 9 of multiplier 10, for adjusting the output frequency of optically pumped laser 2 and exporting the signal generator 11 of square wave synchronizing signal to multiplier 10, for detection signal and square wave synchronizing signal being carried out to the multiplier 10 of multiplying and for the output of multiplier 10 being carried out to filtering and being sent to the low-pass filter 12 of host computer 13.
Pneumatic sample-feeding device comprises cylinder 18, be arranged in cylinder 18 and one end be provided with the sample hose 17 of the piston of cylinder 18 inwalls laminatings, be set in the pre-polarized magnets 19 of annular of cylinder 18 one end and for Quality control pipe 17 at the interior reciprocating drive unit of cylinder 18, on described magnetic shielding sleeve 5, offer through hole, cylinder 18 one end are arranged on caesium atomic vapour bubble 7 tops through through hole.
Cylinder 18 one end are arranged with guiding coil 20, and the other end is arranged with low-angle pulsed coil 21, and described drive unit comprises the solenoid valve 15 that the air compressor of pneumatic supply 14 is provided and is input to the airflow direction of cylinder 18 for switching air compressor 14.
Three groups of Helmholtz coilss 6 comprise three pairs of annular Helmholtz coilss, the center line of every pair of Helmholtz coils overlaps, the center line of three pairs of Helmholtz coilss is mutually vertical, and wherein the center line of a pair of Helmholtz coils and the beam direction of exploring laser light are parallel.
A measuring method of NMR based on laser atomic magnetic force meter, comprises the following steps:
Step 1, control caesium atomic vapour bubble 7 temperature rise to 20-60 DEG C, control Output of laser frequency and the resonance of alkaline metal caesium atom D1 line transition F=4->F '=3 of optically pumped laser 2, and control this resonant frequency of Output of laser frequency departure 100MHz～100GHz of detecting laser 1, electric current to optically pumped laser 2 is modulated, and realizes synchronizable optical pumping;
The angle of step 2, adjustment polarizing prism 3 and quarter-wave plate 4, obtains linear polarization exploring laser light and circularly polarized light;
The angle of step 3, adjustment polarization beam splitter prism 8, until the signal that photodetector 9 is exported is zero;
Step 4, by adjusting the electric current of three groups of Helmholtz coilss 6, make residual magnetic field in magnetic shielding sleeve 5 for minimum, obtain the adjustment electric current of three groups of Helmholtz coilss 6;
Electric current in step 5, the center line of scanning in the three groups of Helmholtz coilss a pair of Helmholtz coils parallel with exploring laser light, the positive current values equating with the negative current magnitude of setting from negative current magnitude to absolute value of setting, be superimposed upon on the adjustment electric current described in step 4, obtain the magnetic field distinguishing signal that low-pass filter 12 is exported;
Step 6, repeating step 2～step 5 be until when unit changes of magnetic field, the changing value maximum of low-pass filter 12 output voltages responses, and the B value of setting range of linearity center, magnetic field is bias magnetic field;
Step 7, get appropriate amount of fluid sample and pour sample hose 17 into, put into cylinder 18;
Step 8, host computer 13 are controlled solenoid valve 15 by relay 16, so control air compressor 14 be blown into the direction in cylinder 18, sample hose 17 is floated to the inside center of the pre-polarized magnets 19 of annular;
Step 9, maintenance sample hose 17 suspension setting-up times, make its fully pre-polarization, host computer 13 is controlled solenoid valve 15 by relay 16, and then change air compressor 14 is blown into the direction in cylinder 18, make sample hose 17 be passed down through guiding coil 20, arrive the top of caesium atomic vapour bubble 7;
Electric current in step 10, control low-angle pulsed coil 21, produces direct current or alternating-current pulse, changes sample magnetic moment direction;
There is the little angle of 5～15 degree in the direction of step 11, sample magnetic moment and bias magnetic field, sample magnetic moment is subject to physically the effect of a moment and does precession around bias magnetic field, and magnetic field is applied to disturbance, obtains the NMR signal of time domain;
The NMR spectrum signal of step 12, NMR signal acquisition frequency field by time domain.
The present invention is a kind of by polarization in advance in tesla magnetic field, uses laser atomic magnetic force meter to detect, and obtains liquid NMR spectrum receiving, thereby detect the method and apparatus of NMR signal in tesla magnetic field.Due to sensitivity and the frequency-independent of laser atomic magnetic force meter, by detect NMR in extremely low magnetic field, can increase the resolution of SNR and spectrum simultaneously, even for very inhomogeneous magnetic field, NMR spectral line is also enough narrow.
The present invention works in ultralow magnetic fields and detects, and is conventionally about 100uT～1nT, and uses 0.1T to polarize in advance to the magnetic field of 2T, and sample volume is very little, from 1cm
3magnitude is to 1mm
3magnitude.Pick-up unit can be designed to a kind of miniature laser atomic magnetic force meter, is that detection probe can be very near the sample under room temperature.
Laser atomic magnetic force meter uses caesium atom as probe bubble actuating medium, it works near room temperature (20～60 DEG C), due to probe and detected sample spatially have distance, therefore very little on the impact of chemistry or biological sample, can ignore.Therefore, sample can lean on very closely with laser atomic magnetic force meter probe, the probe of general laser atomic magnetic force meter can be accomplished 1cm size, sample and probe distance can arrive 1cm, to accomplish 1mm size as the atomic vapour bubble of probe if utilize micro-processing technology, this distance also can narrow down to 1mm, will improve the coupling effect of sample magnetic field and laser atomic magnetic force meter probe, improves the detection sensitivity of NMR signal.Meanwhile, the sensitivity of laser atomic magnetic force meter and the frequency-independent of signal to be detected, can be that several Hz are detected during to hundreds of Hz in Larmor frequency.The magnetic field corresponding with this magnitude Larmor frequency is only in 1mT level, even if the relative homogeneity in this magnetic field (as 1 ‰～1%) is far below the homogeneity (10 of traditional NMR superconducting magnet
-8～10
-6), the NMR signal live width of obtaining is also very narrow, approaches the intrinsic linewidth of nuclear spin resonance.Chemical shift information at low Central Plains daughter nucleus can not show, and only have the scalar coupling irrelevant with magnetic field (as J coupling etc.) information to stay, and these information can provide the characteristic parameter of covalent bond.In a word, the present invention can realize a kind of " key detecting device " that simply utilizes laser atomic magnetic force meter, produces the precise information about heteronuclear scalar coupling in the magnetic field of 100uT to 1nT.
The existing relevant programme proposing from background content part is different, the present invention uses a kind of new actuating medium, utilize its physical characteristics, the probe working temperature of laser atomic magnetic force meter is reduced greatly, to near room temperature, thereby eliminate the spectral line broadening effect to NMR sample to be detected, this working temperature and human body temperature approach in addition, be expected for living body biological application, as human body surface or organ imaging etc.
Present invention includes two large divisions: one is non-linear magneto-optical rotation (the Nonlinear magnetic-optical rotation based on laser and the generation of alkaline metal caesium (Cs) atomic interaction, NMOR) the highly sensitive laser atomic magnetic force counter device part that phenomenon is made, one is pre-polarization and the pneumatic sample-feeding device of sample; Respectively these two devices are carried out to the explanation of operation steps below.
Apparatus of the present invention are by detecting laser 1 and optically pumped laser 2, polarizing prism 3 and quarter-wave plate 4, magnetic shielding sleeve 5 and three groups of Helmholtz coilss 6, caesium atomic vapour bubble 7, polarization beam splitter prism 8 and photodetector 9, multiplier 10 and signal generator 11, low-pass filter 12 and host computer 13, air compressor 14, solenoid valve 15 and relay 16, sample hose 17 and cylinder 18, the pre-polarized magnets (Nd-Fe-B permanent magnet) 19 of annular, guiding coil 20 and low-angle pulsed coil 21 form.Optically pumped laser 2, by after quarter-wave plate 4, is polarized with the atom effect in caesium atomic vapour bubble 7, and signal generator 11 sine wave output signals, to optically pumped laser 2, are modulated its output frequency; Magnetic shielding sleeve 5 is wrapped up centered by caesium atomic vapour bubble 7, and the remnant field of 1nT level is provided, three groups of Helmholtz coilss 6 with added the current source that resistance forms by dry cell and be connected, produce the remnant field of field compensation magnetic shielding; Detecting laser 1 produces laser and acts on it by entering caesium atomic vapour bubble 7 after polarizing prism 3, transmitted light through vapour bubble arrives polarization beam splitter prism 8, after beam splitting, be irradiated to above photodetector 9, produce output current through photoelectric effect and flow into multiplier 10, carry out multiplying with the synchronizing signal of carrying out automatic signal generator 11, output to low-pass filter 12, produce desired signal by host computer 13 records.The pre-polarization of sample and pneumatic sample-feeding device and laser atomic magnetic force counter device keep electrical isolation, but sample hose can arrive via pneumatic sample-feeding device the top of caesium atomic vapour bubble 7, the sample magnetic moment Larmor precession signal producing that polarizes is in advance detected by laser atomic magnetic force meter induction.Pneumatic sample-feeding device connected mode is as described below: air compressor 14 output gas flows are to solenoid valve 15, host computer 13 pilot relays 16 connect from solenoid valve 15 and make it switch different duties, thereby the flow direction of air-flow in five two-way electromagnetic valves switched; Arrive cylinder 18 from solenoid valve air-flow out through tracheae, air-flow promotes sample hose 17 and moves up and down in cylinder, there is a pre-polarized magnets of annular (Nd-Fe-B permanent magnet) 19 cylinder top, sample under air-flow promotes, move downward after by its pre-polarization reach caesium atomic vapour bubble 7 above about 1cm, its magnetic moment precession signal is detected.
In Fig. 1, a is the pre-polarization of sample and pneumatic sample-feeding device, and b is laser atomic magnetic force counter device; Cylinder (18 in Fig. 3) in a is made up of two plexi-glass tubulars that are about 1m, the wherein about 20mm of outer tube diameter, and the about 15mm of diameter of inner pipe, very thin thickness, ignores.On magnetic shielding sleeve (5 in Fig. 2) wall of laser atomic magnetic force counter device b, beat the hole of external diameter 20mm, make the cylinder of pneumatic sample-feeding device can pass this hole, bottom can be adjacent with the probe 7 of laser atomic magnetic force meter, about 10mm, can make like this laser atomic magnetic force meter probe fully interact with sample magnetic field, make fill factor, curve factor maximum, even if also the overall sensitivity of laser atomic magnetic force meter detection NMR signal is the highest.
Claims (4)
1. the NMR device based on laser atomic magnetic force meter, comprise caesium atomic vapour bubble (7), it is characterized in that: comprise the magnetic shielding sleeve (5) being set on caesium atomic vapour bubble (7), be arranged on the three groups of Helmholtz coilss (6) in magnetic shielding sleeve (5), the laser-polarization device of the interior caesium atom of caesium atomic vapour bubble (7) is used for polarizing, for the laser beam emitting device to caesium atomic vapour bubble (7) emission detection laser, for detection of the NMR signal supervisory instrument of the exploring laser light through caesium atomic vapour bubble (7) with for sample being carried out to the pre-pneumatic sample-feeding device that polarizes and the sample after polarizing in advance can be placed into caesium atomic vapour bubble (7) top, laser beam emitting device comprises detecting laser (1) and converts the polarizing prism (3) that is sent to caesium atomic vapour bubble (7) after linear polarization exploring laser light for the laser that detecting laser (1) is sent to, NMR signal supervisory instrument comprises the polarization beam splitter prism (8) for the linear polarization exploring laser light that passes caesium atomic vapour bubble (7) is carried out to beam splitting, for detection of the linear polarization exploring laser light after beam splitting and detection signal is sent to the photodetector (9) of multiplier (10), be used for adjusting the output frequency of optically pumped laser (2) and export the signal generator (11) of square wave synchronizing signal to multiplier (10), for detection signal and square wave synchronizing signal being carried out to the multiplier (10) of multiplying and for the output of multiplier (10) being carried out to filtering and being sent to the low-pass filter (12) of host computer (13), three groups of Helmholtz coilss (6) comprise three pairs of annular Helmholtz coilss, the center line of every pair of Helmholtz coils overlaps, the center line of three pairs of Helmholtz coilss is mutually vertical, wherein the center line of a pair of Helmholtz coils and the beam direction of exploring laser light are parallel.
2. a kind of NMR device based on laser atomic magnetic force meter according to claim 1, is characterized in that: described laser-polarization device comprises optically pumped laser (2) and is converted to the quarter-wave plate (4) that is sent to caesium atomic vapour bubble (7) after circularly polarized light for the laser that optically pumped laser (2) is sent.
3. a kind of NMR device based on laser atomic magnetic force meter according to claim 1, it is characterized in that: described pneumatic sample-feeding device comprises cylinder (18), be arranged in cylinder (18) and one end is provided with and the sample hose (17) of the piston of cylinder (18) inwall laminating, be set in the pre-polarized magnets of annular (19) of cylinder (18) one end and for Quality control pipe (17) reciprocating drive unit in cylinder (18), on described magnetic shielding sleeve (5), offer through hole, cylinder (18) one end is arranged on caesium atomic vapour bubble (7) top through through hole, cylinder (18) one end is arranged with guiding coil (20), the other end is arranged with low-angle pulsed coil (21), described drive unit comprises the solenoid valve (15) that the air compressor of pneumatic supply (14) is provided and is input to the airflow direction of cylinder (18) for switching air compressor (14).
4. a measuring method of the NMR based on laser atomic magnetic force meter, is characterized in that, comprises the following steps:
Step 1, control caesium atomic vapour bubble (7) temperature rise to 20-60 DEG C, control Output of laser frequency and the resonance of alkaline metal caesium atom D1 line transition F=4->F '=3 of optically pumped laser (2), and control this resonant frequency of Output of laser frequency departure 100MHz～100GHz of detecting laser (1), electric current to optically pumped laser (2) is modulated, and realizes synchronizable optical pumping;
The angle of step 2, adjustment polarizing prism (3) and quarter-wave plate (4), obtains linear polarization exploring laser light and circularly polarized light;
The angle of step 3, adjustment polarization beam splitter prism (8), until the signal of photodetector (9) output is zero;
Step 4, by adjusting the electric current of three groups of Helmholtz coilss (6), make residual magnetic field in magnetic shielding sleeve (5) for minimum, obtain the adjustment electric current of three groups of Helmholtz coilss (6);
Electric current in step 5, the center line of scanning in the three groups of Helmholtz coilss a pair of Helmholtz coils parallel with exploring laser light, the positive current values equating with the negative current magnitude of setting from negative current magnitude to absolute value of setting, be superimposed upon on the adjustment electric current described in step 4, obtain the magnetic field distinguishing signal of low-pass filter (12) output;
Step 6, repeating step 2～step 5 be until when unit changes of magnetic field, the changing value maximum of low-pass filter (12) output voltage response, and the B value of setting range of linearity center, magnetic field is bias magnetic field;
Step 7, get appropriate amount of fluid sample and pour sample hose (17) into, put into cylinder (18);
Step 8, host computer (13) are controlled solenoid valve (15) by relay (16), and then control air compressor (14) be blown into the direction in cylinder (18), sample hose (17) is floated to the inside center of the pre-polarized magnets of annular (19);
Step 9, maintenance sample hose (17) suspension setting-up time, make its fully pre-polarization, host computer (13) is controlled solenoid valve (15) by relay (16), and then change air compressor (14) is blown into the direction in cylinder (18), make sample hose (17) be passed down through guiding coil (20), arrive the top of caesium atomic vapour bubble (7);
Electric current in step 10, control low-angle pulsed coil (21), produces direct current or alternating-current pulse, changes sample magnetic moment direction;
There is the little angle of 5～15 degree in the direction of step 11, sample magnetic moment and bias magnetic field, sample magnetic moment is subject to physically the effect of a moment and does precession around bias magnetic field, and magnetic field is applied to disturbance, obtains the NMR signal of time domain;
The NMR spectrum signal of step 12, NMR signal acquisition frequency field by time domain.
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| CN201210291150.3A CN102830381B (en) | 2012-08-15 | 2012-08-15 | Nuclear magnetic resonance (NMR) device and measurement method based on laser atomic magnetometer |
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| CN201210291150.3A CN102830381B (en) | 2012-08-15 | 2012-08-15 | Nuclear magnetic resonance (NMR) device and measurement method based on laser atomic magnetometer |
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| CN102830381B true CN102830381B (en) | 2014-11-12 |
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