JP2013037841A - Specimen cooling holder for transmission electron microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a specimen cooling holder for a transmission electron microscope capable of rotating a specimen freely by 360 degrees in a microscope while cooling the specimen with a cooling medium without dissipating the cooling medium, and to provide a specimen cooling holder which inhibits adhesion of frost to the specimen surface.SOLUTION: The specimen cooling holder for a transmission electron microscope comprises a refrigerant tank, a cooling section which penetrates the refrigerant tank and whose inner wall has a cylindrical cavity, and a heat conduction rod fitted movably in the cavity of the cooling section while sandwiching a good heat conductivity material layer from and to the inner wall of the cavity. The specimen cooling holder includes a pipe for housing the heat conduction rod, and the heat conduction rod has a specimen attachment part at the tip thereof for attaching a specimen.

Description

  The present invention relates to a sample cooling holder for a transmission electron microscope. The present invention also relates to a sample cooling holder for a transmission electron microscope that effectively suppresses frost adhesion to a cooled sample.

  When observing a sample with a transmission electron microscope, the sample is frozen with liquid refrigerant such as liquid nitrogen and observed while cooling to suppress sample damage caused by electron beams in observing biological samples that contain a lot of moisture. Can be expected. However, there is a problem that frost tends to adhere to the sample surface in a series of operation processes in which the sample is frozen, mounted on the sample cooling holder, and set on the transmission electron microscope, making it difficult to observe the sample.

  Therefore, a sample cooling holder for suppressing frost adhesion has been proposed. FIG. 3 is a cross-sectional view showing the structure of a conventional sample cooling holder for a transmission electron microscope (see Patent Document 1). As shown in FIG. 3A, the sample cooling holder includes a refrigerant tank 38 and a heat conduction rod 37 that is fixed to the refrigerant tank 38 and is cooled by the refrigerant tank 38. Moreover, it has a pipe part 36 for accommodating the heat conducting rod 37 therein, and a refrigerant such as liquid nitrogen is supplied to the refrigerant tank 38 through an inlet 39.

  FIG.3 (b) is the elements on larger scale of IIIB in Fig.3 (a). Moreover, FIG.3 (c) is sectional drawing by IIIC-IIIC in FIG.3 (b). At the tip of the heat conduction rod 37, there is a sample mounting portion 31 for mounting the sample 35, as shown in FIG. Since the heat conducting rod 37 is basically fixed to the sample cooling holder, the position of the sample 35 at the tip of the heat conducting rod 37 is also fixed. As shown in FIG. 3C, a slide cap 32 is disposed around the sample mounting portion 31, and the slide cap 32 freely slides on the sample mounting portion 31.

  The slide cap 32 is urged in the direction of arrow A by an internal spring 32b, and is arranged closest to the arrow A by a stopper 34. The slide cap 32 includes upper and lower windows 32a through which electron beams pass. However, when the slide cap 32 is positioned closest to the arrow A by the spring 32b, the sample mounting portion 31 is exposed from the outside air by the slide cap 32. Blocked. For this reason, the adhesion of frost to the sample 35 is suppressed.

  When the sample cooling holder is set in a transmission electron microscope and the tip of the slide cap 32 is pushed in the direction of arrow B shown in FIG. 3B, the slide cap 32 slides on the sample mounting portion 31 and the electron When the line passing window portions 32a are arranged above and below the sample 35, observation with an electron microscope becomes possible.

JP-A-6-76777

  When observing a sample with a transmission electron microscope, it is possible to observe the sample from different directions by rotating the sample around the sample holder axis in the microscope and tilting the sample with respect to the electron beam. Become. However, in the sample cooling holder described in Patent Document 1, the heat conducting rod 37 is fixed to the refrigerant tank 38 as shown in FIG. Naturally, there is a limit to tilting without dissipating the refrigerant.

  An object of the present invention is to provide a sample cooling holder for a transmission electron microscope that can rotate a sample 360 degrees freely in a microscope without dissipating the refrigerant while cooling the sample with the refrigerant. . It is another object of the present invention to provide a sample cooling holder for a transmission electron microscope that suppresses the attachment of frost to the sample surface in the process of attaching a frozen sample to the sample cooling holder and setting the sample on a transmission electron microscope.

  A sample cooling holder for a transmission electron microscope according to the present invention includes a refrigerant tank, a cooling part that penetrates the refrigerant tank and has an inner wall having a cylindrical cavity, and a cavity between the cooling part and the inner wall of the cavity. And a heat conduction rod that is movably fitted with the heat conductive material layer interposed therebetween. In addition, the sample cooling holder includes a pipe portion that accommodates the heat conducting rod therein, and the heat conducting rod has a sample mounting portion for mounting the sample at the tip. The heat conductive material layer to be used is preferably a metal fiber layer containing at least one of copper and aluminum.

  The sample cooling holder of the present invention preferably has a mode in which a pipe portion is fixed to the sample cooling holder and a window portion through which an electron beam passes is provided at the tip. In such an embodiment, when the sample is observed by moving the heat conduction rod forward or backward in the longitudinal direction in the pipe portion, the heat conduction rod is irradiated so that the sample is irradiated with the electron beam through the window portion of the pipe portion. Arranged and this heat conducting rod can be freely rotated in the pipe section. On the other hand, when not observing the sample, a heat conducting rod is arranged so that the sample is cut off from the outside air by the pipe portion. Further, it is preferable that the sample cooling holder includes a cartridge to which the sample mounting portion is attached, and the cartridge to which the sample mounting portion is attached is attached to the heat conducting rod in a cooled state.

  The sample cooling holder for the transmission electron microscope of the present invention can rotate the sample 360 degrees freely in the microscope without dissipating the refrigerant while cooling the sample with the refrigerant. The sample can be observed while changing the sample inclination angle. Further, in the process of mounting the frozen sample on the sample cooling holder and setting it on the transmission electron microscope, it is possible to suppress frost adhesion to the sample surface.

It is sectional drawing of the sample cooling holder for transmission electron microscopes of this invention. It is a fragmentary sectional view which shows arrangement | positioning of the cooling part in the sample cooling holder for transmission electron microscopes of this invention. It is sectional drawing which shows the structure of the sample cooling holder for the conventional transmission electron microscopes. It is the elements on larger scale of the front-end | tip of the pipe part 6 in FIG. It is sectional drawing which shows the aspect in which the sample cooling holder for transmission electron microscopes of this invention is equipped with a cartridge.

  FIG. 1 is a cross-sectional view of a sample cooling holder for a transmission electron microscope of the present invention. FIG. 1 (a) shows a state when a sample is observed with an electron microscope, and FIG. The state when the sample is not observed, that is, the state where the shutter is closed and the sample is shielded from the outside air is shown. As shown in FIG. 1, the sample cooling holder includes a refrigerant tank 8, a cooling unit 1 disposed through the refrigerant tank 8, a heat conduction rod 7 fitted into the cooling unit, and a heat conduction rod 7. The pipe part 6 accommodated in is provided.

  A refrigerant 9 such as liquid nitrogen or liquid helium is injected into the refrigerant tank 8. The refrigerant tank 8 is accommodated in the pressure-resistant container 18, and the pressure-resistant container 18 is adjusted to a vacuum in order to keep the refrigerant tank 8 at a low temperature. The cooling unit 1 is disposed in a state of penetrating the refrigerant tank 8, the heat conducting rod 7 is fitted into the cooling unit 1 to cool the heat conducting rod 7, and a sample attached to the tip of the heat conducting rod 7 is attached. Keep it cool. The heat conducting rod 7 is kept at a low temperature by keeping the inside in a vacuum and keeping the heat insulating property inside the pipe portion 6, and at the time of mounting the sample or setting the sample cooling holder on the electron microscope, Mechanically protect the sample and heat transfer rod.

  FIG. 2 is a partial cross-sectional view showing the arrangement of the cooling unit in the sample cooling holder for the transmission electron microscope of the present invention. As shown in FIG. 2, the cooling part 1 penetrates the refrigerant tank 8, and the inner wall 1a has a cylindrical cavity. A cylindrical heat conduction rod 7 is fitted in the cylindrical cavity of the cooling unit 1, and the heat conductive material layer 3 is provided between the outer wall of the heat conduction rod 7 and the inner wall 1 a of the cavity. For this reason, the cooling unit 1 is cooled by the cryogenic refrigerant 9, and the heat conducting rod 7 is cooled to an extremely low temperature through the thermally conductive material layer 3. In the example shown in FIG. 2, the cooling unit 1 is a block-shaped member whose inner wall has a cylindrical cavity, but instead of the block-shaped member, a pipe whose inner wall is cylindrical as shown in FIG. 1. It can also be used.

  A metal can be preferably used for the heat conductive material layer 3 in terms of high thermal conductivity. Further, among metals, a metal containing at least one of copper (Cu) and aluminum (Al) is more preferable because the cooling efficiency of the heat conducting rod 7 is high. That is, a metal containing Cu, Al, or an alloy of Cu and Al is suitable for the thermally conductive material layer 3. The thermal conductivity of Cu is 398 W / mK, the thermal conductivity of Al is 236 W / mK, and it can be preferably used for a heat conductive material layer because it has a large thermal conductivity among metals and is relatively inexpensive. . The thermally conductive material layer can contain other metals such as silver, gold, and iron as required. The heat conductive material layer 3 is made of a cotton-like fiber layer, so that the cushioning property is improved, the sliding property of the heat conducting rod 7 fitted in the cavity of the cooling unit 1 is improved, and the heat conducting rod 7 is It is held rotatably and facilitates movement in the longitudinal direction. For example, when Cu is used as the material, the layer made of fibers having a wire diameter of about 20 μm can be preferably used as the cotton-like heat conductive material layer 3.

  As shown in FIG. 1, the heat conducting rod 7 has a sample mounting portion 13 for mounting a sample at the tip. In the sample cooling holder for the transmission electron microscope of the present invention, the heat conducting rod 7 is rotatably held in the cavity of the cooling unit 1. Therefore, by cooling the heat conducting rod 7 with the refrigerant 9 and cooling the sample mounted on the tip of the heat conducting rod 7 while rotating the heat conducting rod 7 by the driving unit 17, the refrigerant 9 is not dissipated. The sample can be freely rotated 360 degrees in the microscope. Therefore, by arbitrarily tilting the sample with respect to the electron beam, the observation direction of the sample can be changed by 360 degrees, and the fine tomographic structure or three-dimensional structure of the sample can be observed in detail.

  The sample cooling holder of the present invention is illustrated in FIG. In the example shown in FIG. 1, in the sample cooling holder, the pipe portion 6 is fixed to the sample cooling holder (main body). 4 is a partially enlarged view of the tip of the pipe portion 6 in FIG. 1, FIG. 4 (a) is a partially enlarged view of IVA in FIG. 1 (a), and FIG. 4 (b) is FIG. 4 is a partially enlarged view of IVB in FIG. As shown in FIG. 4, the heat conducting rod 7 has a sample mounting portion 13 for mounting the sample 11 at the tip, and the pipe portion 6 includes a window portion 12 through which an electron beam passes. Since the pipe portion 6 is fixed to the sample cooling holder (main body), the position of the window portion 12 in the sample cooling holder (main body) is also fixed.

  FIG. 1A shows a state when the sample is observed with an electron microscope, and FIG. 1B shows a state when the sample is not observed. Accordingly, FIG. 4A shows the state of the tip of the pipe portion 6 when the sample is observed with an electron microscope, and FIG. 4B shows the tip of the pipe portion 6 when the sample is not observed. Shows the state.

  In the sample cooling holder of the present invention, the heat conducting rod 7 is movably fitted into the cavity of the cooling unit 1. Therefore, the heat conduction rod 7 is held in the pipe portion 6 so as to be movable in the longitudinal direction. When observing the sample, the heat conducting rod 7 is moved backward by the driving unit 17 and the heat conducting rod 7 is arranged as shown in FIG. When the heat conducting rod 7 is moved backward in the direction of arrow C and arranged as shown in FIG. 1A, the sample 11 in the sample mounting portion 13 at the tip of the heat conducting rod 7 is moved as shown in FIG. 4A. Since it arrange | positions in the site | part of the window part 12 of the front-end | tip of a pipe part, the electron beam which passes the window part 12 irradiates the sample 11, and the sample 11 can be observed. This heat conducting rod can be freely rotated in the pipe portion.

  On the other hand, when the sample is not observed, the heat conduction rod 7 is advanced by the drive unit 17 and the heat conduction rod 7 is arranged as shown in FIG. When the heat conducting rod 7 is advanced in the direction of the arrow D and arranged as shown in FIG. 1B, the sample 11 and the sample mounting portion 13 are placed at the tip of the pipe portion 6 as shown in FIG. Since it enters and is sealed in the room, the sample 11 is blocked from the outside air by the pipe portion 6. Therefore, the adhesion of frost to the sample 11 due to the outside air can be effectively suppressed.

  FIG. 5 is a cross-sectional view showing an aspect in which a sample cooling holder for a transmission electron microscope of the present invention includes a cartridge. FIG. 5A shows a state before the sample 11 is attached to the tip of the heat conduction rod 7, and FIG. 5B shows a state after the sample 11 is attached to the tip of the heat conduction rod 7. In the example shown in FIG. 5, in addition to the sample mounting portion 13 for mounting the sample 11 and the heat conducting rod 7, a cartridge 14 is provided, and the tip of the heat conducting rod 7 is molded according to the shape of the cartridge 14, and a leaf spring or the like The elastic member 15 is provided.

  As shown in FIG. 5 (a), after the sample mounting portion 13 for mounting the sample 11 is set on the cartridge 14, the sample 11 is moved in the direction of the arrow E, as shown in FIG. 5 (b). It can be attached to the heat conduction rod 7. After mounting the sample 11 to the sample mounting portion 13 in this way, if the cartridge 14 to which the sample mounting portion 13 is mounted is attached to the heat conducting rod 7 in a cooled state, the sample can be easily handled at extremely low temperatures, Since the time required for attaching the sample can be shortened, adhesion of frost to the sample can be further suppressed.

  Providing a specimen cooling holder for a transmission electron microscope that can observe the minute tomographic structure or three-dimensional structure of a specimen in detail while reducing the damage caused by electron beams by cooling biological specimens containing a lot of water be able to. Further, it is possible to provide a sample cooling holder that can effectively prevent frost from adhering to the sample surface.

DESCRIPTION OF SYMBOLS 1 Cooling part 1a Inner wall 3 Thermally conductive material layer 6 Pipe part 7 Thermal conduction rod 8 Refrigerant tank 9 Refrigerant 11 Sample 12 Window part 13 Sample mounting part 14 Cartridge 15 Elastic member 17 Drive part 18 Pressure-resistant container 31 Sample mounting part 32 Slide cap 32a Window portion 32b Spring 34 Stopper 35 Sample 36 Pipe portion 37 Heat conduction rod 38 Refrigerant tank

Claims (4)

A refrigerant tank;
A cooling section that penetrates the refrigerant tank and has an inner wall having a cylindrical cavity;
In the cavity of the cooling part, a heat conduction rod that is movably fitted with a thermally conductive material layer sandwiched between the inner wall of the cavity, and
A pipe portion for accommodating the heat conducting rod therein,
The heat conducting rod is a sample cooling holder for a transmission electron microscope having a sample mounting portion for mounting a sample at the tip.   The sample cooling holder for a transmission electron microscope according to claim 1, wherein the thermally conductive material layer is a metal fiber layer containing at least one of copper and aluminum. The pipe part is fixed to a sample cooling holder, and the pipe part includes a window part through which an electron beam passes,
By advancing or reversing the heat conducting rod longitudinally within the pipe section,
When observing the sample, the heat conduction rod is arranged so that the electron beam irradiates the sample through the window portion of the pipe portion, and the heat conduction rod can be freely rotated in the pipe portion,
The sample cooling holder for a transmission electron microscope according to claim 1 or 2, wherein when the sample is not observed, the heat conducting rod is arranged so as to block the sample from the outside air by a pipe portion.   The sample cooling holder for a transmission electron microscope according to any one of claims 1 to 3, further comprising a cartridge to which the sample mounting portion is attached, and the cartridge to which the sample mounting portion is attached is mounted on the heat conducting rod in a cooled state.

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