KR20060093785A - High resolution atom trap-mass spectrometry - Google Patents

Abstract

The present invention relates to a high resolution atomic capture-mass spectrometry method, and more particularly, to (1) an isotope-selective capture of neutrons having a plurality of isotopes, and ionizing them to select them according to their mass. Doing; (2) magnetically optically capturing specific isotopes among the plurality of isotopes generated from the neutral atom beam generator; (3) photoionizing the neutral atoms by injecting an ionizing laser beam into the trapped atomic cloud; And (4) screening the ionized isotope ions according to their mass in a mass spectrometer. According to the present invention, it is possible to measure the radioactivity of the radioactive isotopes including Sr-90 isotopes, which are present in trace amounts in nature, and to reduce the analysis time. It can provide an advantage to increase.

Atomic capture, but reducer, mass spectrometer, strontium, cesium

Description

High Resolution Atom Trap-Mass Spectrometry

1 is a conceptual diagram of an atomic capture-mass spectrometry method according to an embodiment of the present invention;

2 is a conceptual diagram of an atomic trap-ionization and ion accelerator device according to an embodiment of the present invention; And

Figure 3 is a mass spectrometer according to one embodiment of the present invention: Figure 3a shows a time- flying mass spectrometer; 3B shows magnetic sector mass spectrometers, respectively.

* Brief description of the main symbols in the drawings *

10: Neutral Atomic Beam Generator 20: Zeman Reducer

30: turbo pump 40: rotary pump

50: ion pump 60: capture chamber

70: acceleration plate 80: mass spectrometer direction

91: capture and deceleration laser 93: atomic beam collimation laser beam

95: atomic beam deflection laser beam 100: neutral atom deflection chamber

110: ionization laser 120: light pumping laser

130: electro-mechanical shutter

140: Acousto Optic Modulator

210: neutral atomic beam 220: half-helm Helms coil

230: ion accelerator plate 240: ion deflection plate

250: deceleration light 260: captured light

271 power supply for supplying voltage to the accelerator

273 power supply for supplying voltage to the deflection plate

275 power supply for supplying voltage to the deflection plate

280: mass spectrometer 290: ionization laser beam

310: TOF chamber 320: ion sensing device

410: Magnetic Sector Mass Separator

420: ion detection device

430 magnetic field

The present invention relates to a method of high resolution atomic capture-mass spectrometry with improved isotope selectivity, and more particularly, (1) isotope-selective capture of a neutral atom having a plurality of isotopes and ionized it to its mass. Providing a device for sorting accordingly; (2) magnetically optically capturing specific isotopes among the plurality of isotopes generated from the neutral atom beam generator; (3) photoionizing the neutral atoms by injecting an ionizing laser beam into the trapped atomic cloud; And (4) screening the ionized isotope ions according to their mass in a mass spectrometer.

Methods to analyze trace isotopes include Accelerator Mass Spectrometry (AMS), Atom Trap Trace Analysis (ATTA), Mass Spectrometer, and radiochemical methods. Representative.

The AMS is sent to the valence particle accelerator extracted from the sample, where all the electrons are released and the mass is measured by the detector. Although the AMS has excellent selectivity, there is a problem in that a large particle accelerator device is required, and in particular, there is a problem of signal overlap due to isobars of elements and molecules of the same mass, which is very difficult to apply this method. Makes it difficult.

ATTA technology decelerates the generated neutrons within the depth of capture with the laser beam facing within the magnetic field environment and uses a circularly polarized, red frequency-shifted laser beam in six directions from the center of the Anti-Helmholtz Coil. As a method of capturing at a point in space, there is an example of krypton and calcium analysis. In the case of krypton, the selectivity is good enough to theoretically obtain a selectivity of 10 ¹⁸ , but the problem with this method is that the selectivity in the first capture is about 10 because the selectivity is low due to the spectral characteristics of the Sr (strontium) element. ^{Only three} are expected. 717 nm re-pumped with laser light _{^{(4d 1 D 2 - 6p 1}} P 1) and _{^{707 nm (5p 3 P 2 -}} 6s 3 S 1) using the re-pumped with laser light and with a secondary capture of In this case, the selectivity can be further increased, but it is generally difficult to reach the selectivity 10 ¹⁰ required for the analysis of the isotope Sr-90 (strontium-90).

There are various methods of mass spectrometry such as magnetic separation method and time flight method. The former is a method in which ions incident on a magnetic field are separated according to mass at a constant speed. Although a difference of about 10 ⁵ according to the electronic apparatus in a manner to separate by the difference in degree different acceleration - can be obtained, the selectivity of 10 ⁷ or so, the latter in to obtain a selectivity of about 10 ³ to 10 ⁴ . However, despite the recent development of various ionization and mass spectrometry methods, it is not possible to measure trace radioactive isotopes such as Sr-90, Cs-133,137, Kr-81,85, Ca-41, etc. There is still a problem that does not solve the superposition of signals by isobars.

Radiochemical methods are currently used to analyze Sr-90 (Strontium-90) isotopes, using chemical purification methods to separate elements (eg, Sr) from soil, milk, and air. In this case, elements having similar chemical properties (eg, Ca) are extracted together when they have similar chemical properties with isotopes (eg, Sr) to be analyzed. In this case, several purification processes are required. In other words, the purification process must be repeated to reduce the error due to the radiation dose from calcium and other elements, and since the radiation is measured after the radiation equilibrium has been achieved, it takes a long time to measure the radiation after purification. If the amount of extract is small, it is difficult to measure.

Steppen Wolf et al., A device for measuring the recoil velocity generated when ionizing trapped Rb atoms using a laser and then measuring the temporal progression of ions using a time flight method ("Ion -Recoil energy measurement in photoionization of laser-cooled rubidium ", Steffen Wolf and Hanspeter Helm, Physical Review A , 56, 6 (1997) R4385), which is independent of mass spectrometry.

Takekoshi et al. Reported a method for measuring Cs molecules generated by capturing a large amount of Cs atoms by ionization and time flight method, and distinguished between Cs atoms and Cs molecules by the time required for natural divergence ("Observation of Optically Trapped Cold Cesium Molecules ", T. Takekoshi, BM Patterson, and RJ Knize, Physical Review Letters , 81, 23 (1998) p5105).

On the other hand, among the devices for high sensitivity analysis of cesium (Cs) isotope, there is a device that combines a magneto-optical trap with a mass-separator ("Magneto-Optical Trap and Mass-separator system for the ultra-sensitive detection of 135Cs and 137Cs ", Applied Physics B, 76 (2003) p.45). The document describes the ionization of ionized atoms through mass spectrometry to increase the selectivity of Cs isotopes, injects ions into the catcher foil, and magnetically optically captures the neutral atoms released by the heating method. A method of doing this is disclosed.

However, the device can only be used in a continuous device such as a magnetic sector separator (Magnetic Sector Separator), the ions captured in the catcher foil must be released again to take the magneto-optical capture, this process is an element that becomes a cell capture It is difficult to apply precooling and collimation in order to increase the efficiency of the magneto-optical capture because it is applicable only to.

Accordingly, the present inventors have improved the selectivity of radioactive isotopes such as Sr-90, Cs-133, 137, etc., which are present in trace amounts in nature, and have a simple and safe use in radioactive materials to measure environmental radioactivity in real time. High resolution atomic capture-mass spectrometry using ion-enhanced ions as the ion spectrometer for mass spectrometers, while investigating methods to analyze trace amounts of isotopes that can be enhanced with high efficiency. Developed.

Accordingly, the present invention provides a high-resolution atomic capture-mass spectrometry method with improved safety capable of measuring environmental radioactivity in real time by increasing analysis selectivity and reducing analysis time of radioactive isotopes present in trace amounts in nature. There is this.

In order to achieve the above object, the present invention,

(1) isotopically-selectively capturing a plurality of isotopes of neutral atoms, ionizing them and screening them according to their mass;

(2) magnetically optically capturing specific isotopes among a plurality of isotopes generated from the neutral atom beam generator;

(3) photoionizing the neutral atoms by injecting an ionizing laser beam into the trapped atomic cloud; And

(4) It provides a high resolution atomic capture-mass spectrometry method comprising the step of selecting the ionized isotope ions in accordance with the mass in a mass spectrometer.

Hereinafter, the present invention will be described in detail.

The present invention includes a step (step 1) comprising an apparatus for isotope-selectively capturing neutral atoms having a plurality of isotopes, ionizing them and sorting them according to their mass.

Specifically, means for selectively magneto-optically capturing a neutral atom having a plurality of isotopes; Means for photoionizing the captured neutral atoms; And means for screening the ionized isotope ions according to their masses to prepare a high resolution atomic trap-mass spectrometer.

Preferred configurations of the apparatus include, for example, a neutral atom beam generator having a laser system and generating neutral atoms; A rotary pump, a turbo pump, and an ion pump may be mounted at one end of the neutral atom beam generator to create a vacuum degree for the operation of the neutral atom beam generator and capture of the neutral atoms. It may be mounted to one side of the turbopump and may be provided with an atomic beam collimator for lateral cooling the generated atomic beam by the first laser beam and collecting the atomic beam. A neutral atom deflection chamber, which may include an atomic beam deceleration device mounted to one end of the collimator, and may be mounted to one end of the atomic beam deceleration device and for selectively deflecting the traveling direction of the neutral atoms; It may be coupled to one side of the neutral atom deflection chamber and may be provided with a capture chamber having an ion acceleration plate for capturing and ionizing the deflected neutral atoms to accelerate and ionize the ionized atoms into the mass spectrometer. . In addition, a mass spectrometer may be provided to sort the accelerated isotope ions according to their mass.

The present invention includes the step of capturing neutral atoms (step 2). In particular, a plurality of isotope atomic clouds generated from the neutral atom beam generator are magneto-optically captured in the capture chamber. The neutral atom to be captured may be selected from elements capable of capture having a plurality of isotopes. For example, Li, Na, K, Rb, Cs, Fr, Mg, Ca, Sr, Cr, Ag, Yb, He, Ne, Ar, Kr, Xe and the like can be applied to capture, but is not limited thereto. no.

Any method commonly used in the art may be used as the method for capturing the neutral atom, but preferably, a magneto-optical capture method, a capture using an AC magnetic field, a capture using a DC magnetic field, and a dipole capture method Can be used. By capturing neutrons, samples of higher density than the surrounding environment are obtained, and only the isotopes that are desired to be measured by optical methods (excitation using a narrow line of laser light) are matched to the capture conditions. It can increase.

To capture neutrons, low-speed neutrons within the capture depth (typically within a few tens to tens of m / s) should be prepared. In general, an atomic gas at temperature T has atoms within the capture depth determined by the Maxwell-Boltzman distribution, but in order to increase the number of atoms within the capture depth, however, such as a slower (Zeeman Slower) Beam reduction devices can be used. The use of an atomic beam deflection device and an atomic beam collimation device in the deceleration device not only increases the loading efficiency of the atomic beam, but also selectively separates it from other elements before atomic capture while increasing isotope selectivity. May be possible.

Magneto-optical traps, which use the principle of transmitting momentum when light is absorbed by atoms, control the frequency of a quadrupole magnetic field and circularly polarized laser light incident in six directions. Aligning near a line allows the atom to be captured at a point in space. In the magneto-optical trapping method, a laser having a very narrow line width is used as the laser beam. Since the trapped atoms are almost at rest, there is no spreading of the transition line (Doppler broadening) due to the movement of the atoms. Therefore, the transition line width of the atom is as wide as the natural line width, which is effective for isotope selection. In the capture, the capture life time is several tens of ms or more, and reaches several seconds depending on the elements and conditions. That is, since the interaction between the atom and the laser light is made hundreds of thousands or millions of times, the isotope selectivity is excellent. In addition, as described above, the use of a reumping technique for injecting a laser beam having a narrow line width to the upper transition line increases the trapping efficiency of the desired element, thereby increasing the ratio of the desired element and the unwanted element. The selectivity can be further increased.

Ytterbium (Yb), or strontium (Sr), etc. of the elements in the line width is very narrow in speed exists captured before yiseonyi capture possible only smaller, in the case of strontium, the _{^{(5s 2 1 S 0 - 5s5p}} 3 P 1) transition means of lines In this case, the line width of the transition line is very narrow compared to the isotope movement, and thus the isotope's discrimination ability can be improved.

In particular, the laser beam resonates with the transition line of the atom during the neutral atom capture and the atomic beam deceleration, so that it is not necessary to use a pure sample and is physically separated from other elements in the capture process. In other words, the purification process is simplified and is not affected by the isotope, another element of the same mass. Therefore, isotopes, which are a problem in general mass spectrometry, are removed during deflection and deceleration of neutral atoms and trapping of neutral atoms.

Other magnetic fields and dipole capture require pre-cooling process, and can increase isotope selectivity when pre-cooling process uses magneto-optical capture and slow speed reducer, etc. It is possible to increase isotope selectivity.

The present invention includes the step of isotope ionizing a neutral atom in the trapped atomic cloud (step 3). As the ionization method, a method commonly used in the art may be used. Preferably, the strontium atom selected as the capture is ionized using a laser from outside, or in a Rydberg state using a wavelength tunable laser. state) and then ionized using an ionizing laser, or excited in a Lidberg state and ionized using an electric field. In this case, the laser may be generated by one or more pulsed lasers or one or more continuous wave lasers. Since the laser light excites and ionizes only the element interacting with a specific transition line inherent to the atom, it is possible to overcome the problem of signal overlap due to the prior art isotopes. In addition, the same principle, even if the atoms of similar chemical properties because the energy level of the atoms are different from each other to overcome the problem of repeating the purification process in order to reduce the error due to the radiation dose generated in the conventional calcium and other elements can do. Specifically, since the wavelength resonating on the strontium transition line can be said to be a wavelength that does not resonate with calcium at all (minimum intensity), the target isotope (for example, strontium) is trapped, and thus, the wavelength is further compared to other elements (for example, calcium). High selectivity can be obtained.

The ionized isotopes as described above are accelerated using the electrode plate and incident on the mass spectrometer.

The present invention comprises the step of selecting the accelerated isotope ions according to their mass (step 4). In this case, the mass may be analyzed using a mass spectrometer. Mass spectrometers may use other methods of mass spectrometry, such as conventional time of flight (TOF) mass spectrometers, magnetic sector mass spectrometers, and quadrupole mass spectrometers. Therefore, after selectively capturing neutral atoms as described above, isotope selectivity can be further improved by using ionized isotope ions as the ion source of the mass spectrometer. In this case, when using the time-flying mass spectrometer, it can be ionized using a pulse laser, and in other devices, it can be ionized using a pulse laser to generate pulsed ions and a continuous oscillation laser capable of generating continuous ions. . When time-flight analysis is applied, ions must be accelerated at high speeds for isotope mass spectrometry.

Unlike the prior art, the high resolution atomic trap-mass spectrometry method of the present invention combines atomic trapping, ionization, and mass spectrometry, and can greatly improve the selectivity of Sr-90 isotopes. In addition, it can be widely applied to the analysis of trace elements that can be captured, such as Cs-133, 137, Kr-81, 85, and Ca-41. The present invention combines atomic capture and mass spectrometry techniques to enhance isotope selection and mass spectrometry.

In addition, since the present invention can obtain higher selectivity than that made by the magneto-optical trap (MOT) method by using the atom capture, ionization, and mass spectrometer together, the MOT method alone It can be applied to elements such as Sr and Cs that cannot give selectivity. When applied to Kr, Ca, conventional MOT method ("Ultrasensitive Isotope Trace Analysis with a Magneto-Optical Trap", CY Chen, YM Li, K. Bailey, TPO'Connor, L. Young, ZT. Lu, Science, 286 (1999) p.1139; and higher selectivity obtained with "Counting Individual Ca41 Atoms with a Magneto-Optical Trap", Physical Review Letters, 92 (15) (2004) p.153002 / 1-4). You can get it.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the following examples are provided to illustrate the present invention, but the scope of the present invention is not limited or limited by the following examples.

One embodiment for the analysis of Sr-90 isotopes, strontium isotopes, is described below. Transition is possible transition line capture of the line of the strontium atom is ¹ S ₀ - from the ¹ P ₁ state - and ³ P ₁ (wavelength: _{^{689.26 nm), 1 S 0 -}} 1 P 1 transition line (wavelength 460.7 nm) and the ¹ S ₀ There is a decay in the 4d ¹ D ₂ state, and from this state back to the 5p ³ P ₁ , ³ P ₂ state, these lifetimes are very long, over several hundred microseconds.

¹ S ₀ - laser light for capturing a ¹ P ₁ transition lines are to be the line width is very narrow, the frequency stability is maintained at several MHz or less (drift, fluctuation). The laser light for this purpose is made by using a ring dye laser oscillating in a single longitudinal mode, or by amplifying a diode laser light oscillating at 921.4 nm and generating a second harmonic. The laser beam is used to generate a dispersion signal using the dichroism of the strontium gas in a saturation absorption spectrometer using a strontium X or a heat pipe oven. The distributed signal is used as a feedback signal to keep the frequency always on the transition line. Thereby, the laser beam which resonates in a strontium transition line with frequency stability below several MHz or 1 MHz can be obtained.

1 is a schematic diagram of an apparatus for carrying out the method according to the invention. First, the rotary pump 40, the turbo pump 30, and the ion pump 50 are used to maintain the vacuum in the capture chamber 60 and the reducer 20 at about 10 ⁻⁸ Torr. In order to operate and capture the Atomic Beam Generator, the degree of vacuum in the vacuum chamber should be about 10 ^-8 Torr. Therefore, the rotary pump 40 is used to first produce a vacuum of 10 ^-2 Torr or less, and then the turbo pump (30). ) To make a vacuum of 10 ^-7 ~ 10 ^-8 Torr. Then, the ion pump 70 is used to make the vacuum degree below that.

The neutral atom beam generator 10 generates neutral atoms such as strontium atoms by changing the temperature and other generating conditions according to the type of atoms. Frequency-stabilized lasers are required for the manipulation of neutral atoms. The laser should be a laser beam resonating to the target transition line of the target metal, and the frequency stability is made to be around 1 MHz or less by using a frequency stabilization system such as a saturation absorption spectroscopy system. In the saturation absorption spectroscopy stabilization device, the stabilized laser beam is located at the center or the side of the target atom transition line, and the capture frequency and laser beam frequency used for deflection, aiming, alignment, and deceleration of atoms are slightly different. (acousto-optic modulator), EO modulator or diode laser is used to obtain the laser light of the required frequency by using current modulation. The laser beam is a laser beam having a narrow line width that resonates with an intrinsic transition line of an atom, and may be used to optically pump the atom from a ground state to a metastable state or an excited state.

When 93 laser beams are incident on four sides of the atomic beam, the atomic beam that passes through the slit is laterally cooled to decelerate and capture many atomic beams. Although the laser light of 91 is incident in the opposite direction of the atomic beam, the atomic beam is decelerated by the laser light of 91 while passing through the reducer 20. The frequency of the laser light of 91 is determined by the magnetic field conditions. In the atomic beam deflector of 100, the laser beam of 95 is used to change the traveling direction of the decelerated and bunched atomic beam. Since the efficiency and direction are determined by the frequency of the laser light, separation from other atoms and separation from other isotopes are possible.

The deflected atomic beam is incident into a 60 capture chamber, which is equipped with a Van Helmholtz coil. The incident slow atom beam is captured by circularly polarized laser light in six directions, using an AO modulator described above to obtain the frequency of the laser light used. When the re-pumping laser light of 110 is incident on the trapped atomic cloud, the trapping efficiency can be further increased. In some cases, two to three re-pumping lights are used.

The laser light of 120 uses pulsed or continuous oscillation laser light as the laser light to ionize the capture cloud. The generated ions are accelerated in the 70 acceleration plate and enter the 80 mass spectrometry system.

Since the actual sample contains many elements such as calcium in addition to strontium, it is necessary to use the optical atomic beam alignment device and the deflection device to transversely cool or deflect only the specific strontium isotope. Do. Transverse cooling and deflection devices use atomic intrinsic transition lines to classify ellipses, as well as to select isotopes.

Transverse cooling is the transverse cooling of the atomic beam, literally reducing the effect of spreading in the transverse direction as the atomic beam progresses, and serves to reach many atoms in the capture chamber. This can be used before or after the reducer 20, but Figure 1 shows the drawing used before passing the reducer 20.

An atomic beam deflector is also made using an atom transition line, but is used after the reducer 20. The decelerated atoms appear to be bunched in velocity, and because of the small Doppler movement, they can also be deflected by laser light incident at a large angle. This can serve to classify isotopes as well as ellipses.

To capture many atoms, it is necessary to pre-cool to increase the amount of atoms with a velocity within the capture depth. Pre-cooling of atoms can be achieved by means of a Zeman slower and various methods. However, in one embodiment of the present invention, using the speed reducer 20, the magnitude of the magnetic field is about -300 G ( Gaussian) to about 300 G (Gauss) is used. The strength of the magnetic field depends on the nature of the transition line of the atom and varies between atoms, transition lines, and atomic beam sources. The interior is maintained in vacuum so that the atomic beam can pass through. When the atomic beam passes through the speed reducer, the movement of the transition line is caused by the magnetic field. When the laser beam is incident in the direction facing the atomic beam to match the movement of the transition line, the atomic beam is decelerated to several to several tens of m / s. The laser beam may be passed through an AO modulator to obtain a laser beam whose frequency is shifted by passing a laser beam, which has been split from the frequency stabilized laser beam obtained above, into a beam splitter.

Six a ^first frequency shift to red at about 30-40 MHz from P ₁ transition line laser light-slow atom beam, the magnetic field gradient in the center 50-100 G / cm which is incident on the capture chamber strontium ¹ S ₀ When incident in the direction, strontium atoms are trapped at a point in space where the magnetic field is zero.

Using a narrow line of laser light and resonating with the inherent energy levels of the element, calcium, which has similar chemical properties to strontium, is also selected during deceleration, deflection, and capture.

2 is a schematic diagram showing the magnetic field direction of the capture light, the deceleration light, and the anti-Helmholtz Coil and the coupling portion of the capture chamber and the mass spectrometer, such as an ionization laser beam, an ion accelerator plate, an ion beam deflection plate, a mass spectrometer, and the like; to be. FIG. 2 is a diagram illustrating the time sequence without considering the time sequence, in which the ionizing laser beam is incident when ionizing laser beam is incident when the trapping light and the decelerating light are present, and the atomic beam and the decelerating light are blocked after the trapping is performed, After blocking, the current of the Anti-Helmholtz coil, the source of the magnetic field, is cut off, and then ionized laser light is incident, and a strong voltage pulse is applied to accelerate the ions and then enter the mass analyzer through the deflection plate. It involves a series of processes.

It can be ionized using a continuous oscillation laser while capture is in progress. In this case, other mass spectrometers such as a magnetic sector mass separator can be used.

A slow atomic beam of 210 is captured in the center by the circularly polarized laser light (sigma +/-) when it enters the center of the capture chamber (the center portion where the magnetic field is zero in the Van Helmholtz coil). In this figure, the laser light incident in the direction opposite to the atomic beam direction represents the decelerated light in the absence of the atomic beam deflector of FIG. 1 and may or may not pass through the capture chamber in some cases. However, the frequency of the deceleration laser light must be determined so as not to affect the capture even when passing through the capture chamber. After the capture, 290 pulsed laser beams are incident to ionize the captured neutral atoms.

Next, an electric field is applied to the acceleration plate of 271 to accelerate the ions in the x direction, pass an ion deflecting device consisting of 240 to adjust the direction of the ions, and then enter the mass spectrometer.

When the captured atoms are ionized and proceed to minimize the effects of the electric and magnetic fields, they operate in a series of processes such as (capture)-(captured light off)-(magnetic field off)-(ionized laser light incident)-(accelerated electric field application). It is possible to do

Can be made incident again pumping light for increasing the selectivity is then captured the process and slow down the light is blocked formed and strontium ¹ S ₀ - ¹ P ¹ strontium after capture using a _first transition line S ₀ - ³ P ₁ transition line In the case of the secondary capture using the capturing method, the primary capture light may be blocked, the secondary capture may be performed, and after the secondary capture, ionization, acceleration, and mass spectrometry may be used.

The laser beam for capturing an atom of the present invention is a laser beam having a narrow line width that resonates with an intrinsic transition line of an atom while capturing the atom by a magneto-optical method, or by optically pumping from a ground state to a metastable state or an excited state. It may be to capture. Specifically, a method of increasing capture selectivity using re-pumped light is as follows.

¹⁾ 1 S ₀ - 1 when captured by using P ₁ transition line, 4d ¹ D ₂ state, to losses to 4d ¹ D ₂ - 6p ¹ increase the trapping amount of the desired element by the optical pumping by P ₁ state Method of making;

2) ¹ S ₀ - ¹ when captured by using P ₁ transition line, 4d ¹ D ₂ state, to losses to 4d ¹ D ₂ - and only the optical pumping unwanted elements that are to 6p ¹ P ₁ state 4d ¹ D Collecting the desired elements in _two states and then ionizing them;

3) ¹ S ₀ - increasing the catch to the optical pumping only the desired isotope in 6p ¹ P ₁ - from ¹ when captured by using P ₁ transition line, 4d ¹ D ₂ state, 4d ¹ D ₂ to losses in (Same process as [1]), and in the remaining strontium elements attenuated to 5p ³ P _j (j = 1,2) in 4d ¹ D ₂ , 5p ³ P _j (j = 0,2)-6s ³ Collecting only the desired isotopes in the 5p ³ P ₁ state through the optical pumping to the S ₁ state and then attenuating to the ground state to increase the amount of capture of the desired element captured in the ¹ S ₀ ^-1 P ₁ transition line;

4) ¹ S ₀ - ¹ when captured by using P ₁ transition line, to the loss caused by 4d ¹ D ₂ state, 4d ¹ D ₂ - 6p only optical pumping want isotopes that a ¹ P ₁ state, and 4d _{^{1 5p 3 P j (j =}} 1,2) after the decay _{^{state, 5p 3 P j (j =}} 0,2) in the state D ₂ - 6s ³ through the optical pumping of a state S _1, 5p ³ P ₁ after collecting only the desired isotope moving at a slow speed in a state, _¹ S ₀ - ¹ P ¹ transition after increasing the catch of the desired element in the wire, changing the laser frequency of light (in other color) _¹ S ₀ - ³ P ¹ transition Method to increase the isotope selectivity by using the secondary capture line (in the second capture transition line, the line width of the transition line is very narrow compared to the isotope movement. Is high); And

5) ¹ S ₀ - ¹ when captured by using P ₁ transition line, to the loss caused by 4d ¹ D ₂ state, 4d ¹ D ₂ - 6p only optical pumping want isotopes that a ¹ P ₁ state, and 4d ¹ after being attenuated in a state D _{2 ^{5p 3 P j (j = 1,2}} ) _{^{state, 5p 3 P j (j =}} 0,1) - and only ping gwangpeom desired element of a 6s ³ S ₁ states 5p ³ P after collected by quasi-balance condition of the _second state, and a magnetic field captured without a laser light, only the unwanted elements that again _{^{(5p 3 P 2 - 6s 3}} S 1) only re-pumped by a high degree of selection 5p of ³ P ₂ state element How to obtain; And the like can be used.

In case of pumping only the desired isotopes, the frequency of the laser light is precisely matched with the desired isotope transition lines. In case of light pumping only isotopes, the frequency of the laser light is correctly adjusted to the unwanted isotope transition lines. It should be optically pumped. In the case of optically pumping unwanted isotopes, one or more isotopes may be applicable. Therefore, an electro-optic modulator (EO modulator) or an acoustic optical modulator (AO modulator) may be used to generate a laser beam having a frequency suitable for each isotope. Create

3 is a diagram showing methods that can be used in the mass spectrometry method. 3 shows a method using a time flight (TOF) mass spectrometer (a) and a magnetic sector mass separator (b) as a mass spectrometry method. In addition, quadrupole mass spectrometry and other mass spectrometry methods can be used. In case of using time flight method, as mentioned above, pulse type ionization should be performed and pulse laser is used as ionization laser. Other methods may use a continuous ion generation method, for example a magnetic sector mass separator (Magnetic Sector Mass Separator). The present invention is distinguished from conventional mass spectrometry in that isotope screening by capture and ionization laser is used as the ion source of the mass spectrometer.

(a) shows a time- flying mass spectrometer. When ions are incident in the direction of the arrow, they are detected by 320 ion detectors via a tube of 310. The time of flight depends on the mass of each isotope and elements, which are measured in chronological order according to the mass of ions reaching the ion sensing device 320, and various methods of increasing precision may be used.

(b) shows the magnetic sector mass spectrometer. When ions are incident in the direction of the arrow, the ions flying in the magnetic field environment differ in the degree of warpage according to the mass. The mass filter and the slit, etc. are used to pass only the elements of the required mass and are measured by the ion detector of 420. Device.

The present invention is applicable to all elements that can be captured, for example, Li, Na, K, Rb, Cs, Fr, Mg, Ca, Sr, Cr, Ag, Yb, He, Ne, Ar, Kr, Xe, etc. The magneto-optical capture alone, such as krypton (Kr) and calcium, can be applied to elements with large isotope selectivity to further increase the selectivity.

A method of ionizing trapped neutral atoms, the method comprising: directly ionizing a laser beam to a Continuum above an ionization limit; Ionization method by collision of electrons; Resonance ionization method using a tunable laser; Existing ionization methods such as field ionization after excitation in a Rydberg state using a wavelength tunable laser can be applied.

In the mass spectrometer system, a magnetic sector mass spectrometer and a time flight mass spectrometer can be used. It can be applied to other mass spectrometers, such as other quadrupole mass spectrometers. The mass spectrometry system can be selected according to the required selectivity and the size of the experimental apparatus.

According to the high resolution atomic capture-mass spectrometry method of the present invention having the above structure, it is easy to apply precooling and collimation to increase the efficiency of capture, and isotope-selective analysis with high sensitivity and high capture efficiency for specific elements. There is no problem of signal overlap due to isotopes, and it overcomes the drawback that conventional analytical equipment is enlarged, thereby increasing the selectivity and reducing the analysis time of radioisotopes including Sr-90 isotopes, which are present in trace amounts in nature even with simple equipment. In this way, it is possible to measure environmental radioactivity in near real time, thereby improving stability in the use of radioactive materials. In addition, the present invention can be applied to elements that are not trapped, such as Yb, and can be applied to all elements capable of trapping such as Sr, Cs, Rb, Kr, and Ca. Overcoming the shortcomings, the selectivity can be further increased by applying to elements having high isotope selectivity only by magneto-optical capture such as krypton (Kr), calcium (Ca). When capturing is carried out as described above, it is possible to obtain additional functions to increase selectivity and sensitivity to reducers, etc., and to generate pulse-type and continuous ions. It can be used in other mass spectrometers such as air conditioning and other mass spectrometers, and can generate small volumes (about several hundred micrometers) of ions, thereby further improving the resolution of the mass spectrometer. In addition, a series of processes, such as ionization and mass spectrometry, can be performed continuously and simply.

In addition, the present invention may provide advantages that may contribute to the development of geological dating and other pure sciences.

Claims (6)

(1) isotopically-selectively capturing a plurality of isotopes of neutral atoms, ionizing them and screening them according to their mass; (2) selectively magneto-optically capturing specific isotopes among the plurality of isotopes generated from the neutral atom beam generator; (3) photoionizing the neutral atoms by injecting an ionizing laser beam into the trapped atomic cloud; And (4) A high resolution atomic capture-mass spectrometry method comprising the step of selecting the ionized isotope ions according to their mass in a mass spectrometer. 2. The laser beam of claim 1, wherein the laser beam is a laser beam having a narrow line width resonating with an intrinsic transition line of an atom, for capturing the atom by magneto-optical method, or for optically pumping an excited state in a ground state or a metastable state. High resolution atomic capture-mass spectrometry method. The method of claim 1 or 2, wherein the laser beam is generated by one or more pulsed lasers or continuous wave lasers. The method of claim 1, wherein the neutral atom is selected from elements capable of trapping having a plurality of isotopes. Means for selectively magneto-optically capturing a neutral atom having a plurality of isotopes; Means for photoionizing the captured neutral atoms; And means for sorting the ionized isotope ions according to their mass. A high resolution atomic capture-mass spectrometer for carrying out the method according to any one of claims 1 to 4. 6. The apparatus of claim 5, wherein the apparatus comprises a laser system; A neutral atom beam generator for generating neutron atoms; A rotary pump, a turbo pump, and an ion pump mounted at one end of the neutral atom beam generator to create a degree of vacuum for the operation of the neutral atom beam generator and the capture of the neutral atoms; An atomic beam collimator mounted to one side of the turbopump and configured to laterally cool the generated atomic beam by a first laser beam and to collect the atomic beam; An atomic beam deceleration device mounted to one end of the collimator; A neutral atom deflection chamber mounted at one end of the atomic beam reduction apparatus and for selectively deflecting the traveling direction of the neutral atoms; A capture chamber coupled to one side of the neutral atom deflection chamber and having an ion acceleration plate for accelerating and ionizing the ionized atoms into a mass spectrometer as a portion for trapping and ionizing the deflected neutral atoms; And a mass spectrometer for sorting the accelerated isotope ions according to their masses.

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