JP3683716B2 - Thermal insulation structure of NMR probe - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat insulating structure used in a temperature variable type NMR probe.
[0002]
[Prior art]
In order to realize variable temperature measurement with an NMR probe, a heat insulating structure having sufficient performance is required together with a mechanism for heating and / or cooling a sample.
[0003]
FIG. 1 shows an adiabatic structure of a MAS probe for measuring a solid NMR spectrum. The MAS probe is fitted into a cylindrical hole drilled along the axis of a superconducting magnet (not shown), and is installed so that the central axis of the MAS probe and the axis of the static magnetic field created by the superconducting magnet coincide. .
[0004]
The housing 1 of the MAS probe has a rotation axis in a direction inclined by 54.7 ° with respect to the axial direction of the static magnetic field generated by the superconducting magnet, and is rotated at a very high speed (several kilohertz to several tens of kilohertz). It has a structure for obtaining a solid-state NMR spectrum of resolution.
[0005]
In order to measure the sample temperature dependence of the solid-state NMR spectrum, it is necessary to introduce temperature-controlled VT air 2 from below the MAS probe to control the temperature of the entire housing 1. For this purpose, it is indispensable to suppress the exchange of heat with the outside world, and it is necessary to insulate the housing from the outside world with a vacuum double tube 3 made of glass.
[0006]
[Problems to be solved by the invention]
However, since the glass vacuum double tube 3 used for heat insulation is vulnerable to mechanical shock, a breakage accident often occurs during the assembly operation of the MAS probe and use at the customer site. Further, the glass vacuum double tube 3 is expensive because it is difficult to manufacture, and there is a problem that manufacturing troubles due to vacuum failure often occur.
[0007]
On the other hand, as an alternative technique of the glass vacuum double tube 3, a Teflon sheet can be used as a heat insulating structure. However, in the case of a Teflon sheet, it is difficult to set the thickness. When it was too thin, there was a problem that heat insulation was insufficient.
[0008]
In view of the above points, an object of the present invention is to provide a heat insulating structure that has no fear of becoming a source of NMR background signal and has excellent heat insulating properties.
[0009]
[Means for Solving the Problems]
In order to achieve this object, the heat insulating structure of the NMR probe according to the invention of claim 1 is provided with a thermal insulator layer covered with a good electrical conductor layer around the sample chamber of the NMR probe in the temperature variable measurement by the NMR probe. In addition, the inside of the NMR probe and the outside are insulated, and the good electrical conductor layer covering the thermal insulator layer is connected to the ground potential.
[0010]
The heat insulation structure of the NMR probe according to the invention of claim 2 is characterized in that the NMR probe is a MAS probe for measuring a solid sample.
[0011]
The heat insulating structure of the NMR probe according to the invention of claim 3 is characterized in that the good electric conductor layer is made of metal plating.
[0012]
The heat insulating structure of the NMR probe according to the invention of claim 4 is characterized in that the thermal insulator layer is made of a heat resistant resin.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows an adiabatic structure of the NMR probe according to the present invention. In the figure, the same components as those in FIG. 1 will be described with the same numbers as those in FIG.
[0016]
In the figure, reference numeral 1 denotes a MAS probe housing. The housing 1 has a rotation axis in a direction inclined by 54.7 ° from the central axis of the MAS probe, and rotates the measurement sample at a high speed. From below the housing 1, VT air 2 for controlling the sample temperature is supplied. Thereby, the temperature of the internal structure of the MAS probe including the housing 1 can be freely controlled.
[0017]
Around the housing 1, a cylindrical heat insulating material 4 made of heat-resistant resin, which is plated with tin or the like, is disposed at a place where the glass vacuum double tube 3 is conventionally disposed. This metal plating is grounded to an external metal cylinder or the like at the end of the heat insulating material.
[0018]
The temperature-controlled VT air 2 heats and / or cools the NMR sample together with the housing 1 while filling the inside surrounded by the heat insulating material 4. At this time, heat conduction from the MAS probe to the outside or heat conduction from the outside to the MAS probe is blocked by the heat insulating material 4.
[0019]
Although the metal plating applied to the surface of the heat insulating material 4 has high thermal conductivity, the thickness is thin, so that the actual amount of heat conduction is extremely small. In addition, since the high frequency emitted from the NMR signal detector flows to the ground via the metal plating, the heat resistant resin constituting the heat insulating material 4 is not irradiated with the high frequency, and there is no possibility of causing a background signal. Absent. This indicates that the metal plating serves as a shield against high frequencies.
[0020]
Although the heat insulation performance of such a heat insulation structure is slightly inferior to that of the glass vacuum double tube 3, it has a heat insulation performance enough to withstand practical use, and is mechanically better than the glass vacuum double tube 3. In terms of price, it is much more robust and can be manufactured at a very low price.
[0021]
The heat insulating material 4 may be anything as long as it has a low thermal conductivity. The plating may be any material as long as it has a high electrical conductivity.
[0023]
【The invention's effect】
As described above, by using the heat insulating structure of the NMR probe of the present invention, it is possible to overcome the mechanical brittleness and high cost that were the disadvantages of the conventional heat insulating structure using a glass vacuum double tube, In addition, it is possible to obtain a heat insulating performance sufficient for practical use.
[Brief description of the drawings]
FIG. 1 is a diagram showing a heat insulation structure of a conventional NMR probe.
FIG. 2 is a diagram showing an embodiment of the heat insulation structure of the NMR probe of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Housing, 2 ... VT air, 3 ... Glass vacuum double tube, 4 ... Thermal insulation.

Claims (4)

In the temperature variable measurement using the NMR probe, a thermal insulator layer covered with a good electrical conductor layer is disposed around the sample chamber of the NMR probe to insulate the NMR probe from the outside and the thermal insulator layer. An adiabatic structure of an NMR probe, characterized in that a good electrical conductor layer is connected to a ground potential. The heat insulating structure of the NMR probe according to claim 1, wherein the NMR probe is a MAS probe for measuring a solid sample. The heat insulating structure for an NMR probe according to claim 1, wherein the good electric conductor layer is made of metal plating. The heat insulating structure for an NMR probe according to claim 1, wherein the thermal insulator layer is made of a heat resistant resin.

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