JPS6345549A - Coil for nmr - Google Patents

Abstract

PURPOSE:To obtain coils for NMR (nuclear magnetic resonance) which can be arranged nearby each other by eliminating mutual electromagnetic coupling between coils and arc coil parts of the coils. CONSTITUTION:Concentric cylindrical bobbins 1 and 3 are arranged and coils 4 and 5 are arranged so that the direction of an RF magnetic field cross the bobbins at right angles. Then, a shield ring 2 is sandwiched between the bobbins 1 and 3 at the part where the arc coil parts of the coils 4 and 5 face each other. Here, the inside coil 4 is for observation and the outside coil 5 is for irradiation and locking. Consequently, even when the coils 4 and 4 are arranged closely, their electromagnetic coupling which causes mutual problems can be eliminated and the coil 5 is also arranged nearby a sample.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an NMR (nuclear magnetic resonance) coil comprising two sets of coils arranged on a concentric cylinder around the outer periphery of a cylindrical space into which a sample is loaded. .

[Conventional technology]

Fig. 4 is a diagram showing an example of the configuration of an NMR coil, and Fig. 5 is a diagram showing an example of the shape of a conventional NMR coil.
1 and 12 are coils, 13 is an observation terminal, 14 is an irradiation terminal, 15 is a lock terminal, and 16 and 17 are bobbins.

When a nuclear spin system is placed in an external static magnetic field H0, the nuclear magnetization M,
precesses around the static magnetic field H0 at the Larmor frequency of ω・−γH0 (1). Here, T is called the magnetic angular momentum ratio and is a constant specific to each magnetic nucleus. In NMR (nuclear magnetic resonance), when a high frequency magnetic field (radio wave) rotating in a plane perpendicular to the static magnetic field H0 at the same frequency as the Larmor frequency is applied, resonance occurs and energy is absorbed from the high frequency magnetic field. Therefore, in an NMR device, the sample is placed in a -4 magnetic field, and the NM
A resonance frequency is given to the R coil to generate a high frequency magnetic field, and the energy absorbed by resonance is compared horizontally.

The NMR apparatus is equipped with two coils 11 and 12 as NMR coils, as shown in FIG. Then, each coil 11 is used as an observation terminal 1 for observation.
3, and the coil 12 is used for high frequency magnetic field irradiation and for NMR.
It is connected to the irradiation terminal 14 and the locking terminal 15 for locking.

The NMR coils are connected to a concentric cylindrical bobbin 16.1 while keeping an appropriate distance from each other as shown in FIG.
7, and the direction of the RF [field is perpendicular to these (assuming that the ring direction of the cylindrical space is the Z axis and the cross section of the cylindrical space is the XY plane), the RF [field of the coil 11 is in the
The coils 11 and 12 are arranged so that the I field is in the Y direction.

Although not shown, there is also a fifth shape of the NMR coil.
Some coils 11 and 12 are arranged on the inside and outside of a common bobbin 16, 17 shown in the figure, respectively.

[Problem that the invention seeks to solve]

The closer the NMR resonance signal is to the sample, the stronger the signal can be detected. However, since a Helmholtz (horseshoe) shape is adopted as the basic shape, if the coils 11 and 12 are placed too close to each other, they will be placed along the cylindrical cross section as shown in Fig. 5 (bl). Since mutual electromagnetic coupling becomes considerably strong in the arc-shaped arc coil portion, a problem arises in that the resonance signal on the observation side, which is most important, is absorbed by the coil 12, resulting in a decrease in sensitivity.

Conventionally, this problem has been solved by increasing the difference in diameter between the bobbins 16 and 17, as shown in FIG. However, in this case, the distance between them cannot be ignored. This is because the larger the distance between the coils 11 and 12, the more the coils 12
The intensity of the resonance signal detected by the irradiation, NM
This causes a decrease in the efficiency of the Rt:l block and causes a problem different from the above. Therefore, this distance is thick (cannot be taken) at the end of the rod.

The present invention solves the above-mentioned problems, and aims to provide an NMR coil that eliminates mutual electromagnetic coupling in the arc coil portions of the coils 11 and 12 and can be arranged close to each other. It is.

[Means for solving problems]

To this end, the NMR coil of the present invention has two sets of coils, each consisting of an arc-shaped arc coil part and an axial co-coil part parallel to the pongee, arranged in a concentric cylinder around the outer periphery of a cylindrical space in which a sample is loaded. The NMR coil disposed above is characterized in that a shield ring is disposed between the arc coil portions of the 2&ll coils.

[Effect]

In the NMR coil of the present invention, the shield ring is sandwiched between the arc coil parts of the two sets of coils, so there is no electromagnetic coupling even if both coils are placed close to each other, and the resonance signal on the observation side is used for irradiation/locking. It will no longer be absorbed by the coil and cause a decrease in sensitivity. In addition, even if the irradiation/locking coil is placed near the sample, electromagnetic coupling with the observation coil can be blocked and the strength of the resonance signal will not weaken, thus preventing a decrease in the efficiency of irradiation and NMR locking. be able to.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing one embodiment of the NMR coil according to the present invention, FIG. 2 is a circuit diagram of the NMR coil according to the present invention, and FIG. 3 is a diagram showing another embodiment of the shield ring. In figure 0,
1 and 3 are bobbins, 2 is a shield ring, and 4 and 5 are coils.

The NMR coil according to the present invention has concentric cylindrical bobbins 1 and 3 arranged as shown in FIG. is the XY plane, the RF field of the coil 4 is in the X direction,
The coils 4 and 5 are arranged so that the RF magnetic field of the coil 5 is in the Y direction. Then, the bobbin 1 is located at the portion where the arc coil portions of the coil 4 and the coil 5 face each other.
．． The shield ring 2 is sandwiched between the shield rings 3 and 3. Its cross-sectional view (plan view) is shown in Figure 1 ta>, its perspective view is shown in Figure 1 (BL), and its vertical cross-sectional view is shown in Figure 1+C+. The inner coil 4 is for observation, and the outer coil 5 is for irradiation. It is for locking.

As shown in Figure 1 (bl, tc+), a window formed by the arc coil parts of the coils 4 and 5 and the circular coil part parallel to the pongee of the cylindrical space is opened, and a shield ring is formed between the arc coil parts. By sandwiching the coils 4 and 2, an electromagnetic barrier is provided between the arc coil parts.For this reason, even if the coils 4 and 5 are placed close to each other, it is possible to eliminate the electromagnetic coupling that causes problems between them. Since the magnetic coupling with the coil 4 is not conscious, it can be placed near the sample like the coil 4.

The relationship between the arc coil portion and the annular coil portion of each coil 4.5 is shown in FIG. 2. As shown in FIG. 2, the cross-sectional direction (Z) of the arc coil portion is the same for all coils 4.5, whereas the cross-sectional direction (X, Y) of the annular coil portion is The directions are perpendicular to each other.

In the NMR coil of the present invention, a shield shown by dotted lines is provided between the arc coil parts that are electromagnetically coupled in the same direction. Note that this shield may be grounded or floated from the ground.

The shield ring 2 may be a cylindrical pipe as shown in Fig. 2, but if it acts as an electromagnetic barrier between the arc coil parts of the mutual coils, it may be a cylindrical pipe as shown in Fig. 3 (al). You can also prepare a vibrator split in half and use it with the two halves facing each other, or use the
A disc-shaped one as shown in 1 may also be used.

As the shield ring, conductive materials, metals, polymer materials, etc. can be used, and film-like printed boards made of these materials, those deposited on glass or ceramic, or foil-like plates made of glass or ceramic substrates can be used. It may also be attached to.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, in order to cut off electromagnetic coupling caused by the arc coil between the observation coil and the irradiation/locking coil, both coils are placed close to the sample. can. As a result, the sensitivity of the NMR resonance signal in each coil can be increased, and measurement efficiency can be improved. In particular, in conventional NMR coils, between the coils! Since many resonant waves are generated due to magnetic coupling, the generated energy of the desired resonant wave is often absorbed, and the signals of substances in the space outside the detection space are pinked up, causing the tail of the spectrum to widen significantly. Was. However, according to the present invention, a shield ring is provided,
In addition to reducing unnecessary resonance waves, it also blocks the pink-up of signals from outside the detection space, which eliminates the problems with conventional NMR coils and improves measurement sensitivity and efficiency. can.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of the NMR coil according to the present invention, FIG. 2 is a circuit diagram of the NMR coil according to the present invention, and FIG. 3 is a diagram showing another embodiment of the shield ring. , Fig. 4 shows an example of the configuration of an NMR coil, and Fig. 5 shows a conventional NM coil.
It is a figure which shows the example of a shape of the coil for R. 1 and 3...bobbin, 2...shield ring, 4 and 5...
·coil. Applicant: JEOL Ltd. Figure 1 (C) Figure 2 Figure 3 (α) Cb) Figure 4

Claims (1)

[Claims] An NMR coil in which two sets of coils each consisting of an arc-shaped arc coil part and a circular coil part parallel to the pongee are arranged on a concentric cylinder on the outer periphery of a cylindrical space in which a sample is loaded. An NMR coil characterized in that a shield ring is placed between the arc coil portions of the two sets of coils.