JPS5833156A - Detector for nuclear magnetic resonator signal - Google Patents

Abstract

PURPOSE:To detect the excitation of resonance and the detection of two nuclides independently by arranging two coils on a cylindrical surface parallel with the axis of a sample tube diagonally while crossing each other at the right angle while a third coil is arranged on the axis intersecting said two coils at the right angle. CONSTITUTION:A first detection coil is arranged on the outer surface of a first glass cylinder coaxially arranged in the perimeter of a sample tube with the axis thereof parallel to the direction of the electrostatic field in such a manner that the coil surface is at 45 deg. to the axis of the cylinder. A second detection is arranged on the inner surface of a second glass cylinder arranged coaxially in concentric circle with the first glass cylinder in such a manner as to have the coil surface thereof intersection the first detection coil at the right angle. A third coil is arranged in such a direction that it crosses the first and second detection coils cross at the right angle and used for an exciting coil. This eliminates interaction between three coils thereby permitting the excitation of the resonance and the detection of two unclides independently.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-resolution nuclear magnetic resonance signal detector, and particularly to a non-interactive three-coil arrangement.

'When an atomic nucleus with a non-zero spin quantum number such as H, 130 is placed in a static magnetic field and an oscillating magnetic field is applied in a direction perpendicular to the static magnetic field, it resonates at a constant frequency determined by the nuclide and the strength of the static magnetic field. Generates an oscillating magnetic field that is deflected in a direction perpendicular to the static magnetic field. This is the phenomenon of nuclear magnetic resonance. Resonant frequency ω. is ω, where H8 is the static magnetic field strength and r is the gyromagnetic ratio. -rHo. r is a constant specific to the nuclide. The resonance frequency is, for example, 90 MH2 at 1 H and 22.6 MH2 at 2% C in a static magnetic field of 2.1 Tesla.

In a nuclear magnetic resonance apparatus, a coil is placed in a direction perpendicular to a static magnetic field, and a sample is inserted into the coil. The oscillating magnetic field generated in the resonant state creates an induced voltage in the coil, allowing resonance to be detected.

By the way, in a high-resolution nuclear magnetic resonance apparatus, there are cases where it is necessary to measure multiple nuclides simultaneously. For example, this is a measurement in which magnetic field stabilization is performed using resonance signals of 2D nuclei, and resonance signals of 130 nuclei are simultaneously obtained. An example of such a detector is shown in FIG. 1 is a lunoid magnet that generates a static magnetic field, 2 is a sample tube containing a sample to be measured, 3 is a detection coil, 4 is a detection tuning circuit that includes the detection coil as a part, 6 is an excitation coil, and 7 is an excitation tuning circuit It is.

Figure 2 shows an example of a detection tuning circuit. LL is a detection coil that resonates with C1 and C2 at a resonance frequency of 13c. or,
C3 and L2 resonate at +30 resonant frequency and '3C
Separate the receiving system and 2D receiving system.

Furthermore, the entire structure resonates at a 2D resonant frequency.

By the method shown in FIG. 2, it is possible to simultaneously detect two resonances having different resonance frequencies, such as the '3C nucleus and the 2D nucleus. However, in this method, there is a problem in that when the value of C1 is changed in order to adjust the resonant circuit 13c, which is related to each other, the resonant state of 'D also changes. Furthermore, the measurement nuclide is changed from 13c to other nuclides, such as 31.
In the case of changing to p, etc., the values of CI and C2 must be changed significantly, and as a result, the resonance state of the 'D nucleus also changes completely. As described above, the method shown in FIG. 2 has a problem in that it cannot be used at all when changing the nuclide to be measured.

In addition to the above methods, a method shown in FIG. 3 has been proposed.

7 is a detection coil for 2D nuclear detection, and is arranged in a direction perpendicular to the original detection coil 3. However, an excitation coil 5 for exciting normal resonance is arranged in this direction, and the two coils are arranged coaxially. As a result of this mutual coupling of the two coils, problems such as a decrease in excitation efficiency and a decrease in 2D nuclear detection efficiency occur. Furthermore, if heteronuclear-like decoupling or the like is also performed, it is necessary to generate a strong oscillating magnetic field by the excitation coil. In this case, the oscillating magnetic field also generates a large induced current in the 2D nuclear detection coil, heating the coil and reducing detection sensitivity.
Alternatively, it has the disadvantage of saturating the amplifier circuit following the detection tuning circuit.

An object of the present invention is to provide a method for realizing simultaneous detection of two or more nuclides with completely independent configurations.

In the present invention, two sets of coils are arranged diagonally and orthogonally to each other on a cylindrical surface parallel to the sample tube axis, and a third coil is arranged on an axis perpendicular to the above two coils. This makes it possible to excite resonance and detect two nuclides independently.

An embodiment of the invention is shown in FIG. 3 is a first detection coil; 5 is a glass cylinder to which the first detection coil is fixed, and is arranged coaxially with the sample tube 2; 4 is a first detection tuning circuit. 8 is a second detection coil; 10 is a glass cylinder to which the second detection coil is fixed; the glass cylinder is arranged coaxially with the sample tube 2; 9 is a second detection tuning circuit, 6 is an excitation coil, and 7 is an excitation tuning circuit.

In this example, it has an axis parallel to the direction of the silent magnetic field,
A first detection coil is arranged on the outer surface of a first glass cylinder coaxially arranged around the sample tube so that the coil surface forms an angle of 45° to the cylinder axis. Further, a second detection coil is arranged on the inner surface of a second glass cylinder which is arranged coaxially and concentrically with the first glass cylinder so as to have a coil surface perpendicular to the first detection coil. There is.

Generally, there are two types of coupling between two coils: magnetic coupling and electrical coupling.
- ], the magnetic coupling is insignificant, and the electrical coupling does not pose a practical problem since the opposing Lfll is extremely small in this embodiment.

In this embodiment, a third coil is arranged in a direction perpendicular to each of the first and second detection coils and is used as an excitation coil. Since such excitation coils are orthogonal to the first and second coils, there is no interaction between the respective detection coils and the excitation coils, just as there is no interaction between the first and second detection coils. There is also no interaction.

As described above, there is no interaction between the three coils in this embodiment, and they can be treated as completely independent systems. That is, the first detection coil is I3C or 31p.
When the second detection coil is used as a 2D signal system for controlling the magnetic field, even if the resonance frequency of the detection tuning circuit including the first detection coil is changed, the second detection There is no effect on the 2D signal detection tuning circuit including the coil and the excitation tuning circuit including the excitation coil, which makes it possible to measure any nuclide in an extremely stable magnetic field. As mentioned above, nuclear magnetic resonance apparatuses handle oscillating magnetic field components perpendicular to the direction of the static magnetic field for both resonance excitation and detection. Therefore, as long as the coil axis is set in a plane perpendicular to the static magnetic field as in the conventional case, the number of independent coils is limited to two sets. In the present invention, while each coil generates or detects an oscillating magnetic field component in a direction perpendicular to the static magnetic field, the arrangement of the coils also introduces a component parallel to the static magnetic field. This is a practical version of the coil component.

According to the present invention, it is possible to incorporate three independent coils, and a change in the electrical characteristics of a resonant circuit including one coil does not affect other coil systems at all. .

In the embodiment, the first and second coils are arranged at an angle of 45° to the direction of the static magnetic field.
It is not necessary to limit the angle to °; other angles are also possible.

That is, the basic requirement of the present invention is that the first and second coils are diagonal to the direction of the silent magnetic field and are orthogonal to each other.
It is also possible to arrange it at an angle of . This example of changing the angles of the two coils is effective when it is possible to prioritize the detection efficiency of the two signal detection systems.

[Brief explanation of drawings]

FIG. 1 is a layout diagram showing a conventional example, FIG. 2 is a circuit diagram used in the method shown in FIG. 1, FIG. 3 is a layout diagram showing a conventional example, and FIG. It is a layout diagram showing an example of. Figure 1

Claims (1)

[Claims] 1. A first coil having a coil axis parallel to the direction of the static magnetic field and a coil surface obliquely intersecting the axis;
A second coil having a coil surface orthogonal to the first coil surface is arranged around a common axis with the first coil, and further the first and second coil surfaces are arranged on both sides with the first and second coils in between. 1. A nuclear magnetic resonance signal detector characterized in that a coil pair having a coil plane orthogonal to the above is arranged.