SAMPLE CELL, LOADING STATION, MEASURING DEVICE, METHODS FOR EXAMINING AND FOR PRODUCING A FLAT CRYSTAL, USE OF A SAMPLE CELL

Abstract

A sample cell including a sample space, restricted on its first side by a first inner side of a first membrane and on its second side by a second inner side of a second membrane. A spacer is arranged between the first and the second inner sides to establish a distance between the membranes. A first retaining element is arranged on a first outer side, facing away from the sample space, of the first membrane and a second retaining element is arranged on a second outer side, which faces away from the sample space, of the second membrane, the first and second retaining elements together form a retaining structure. The first and second retaining elements each have a plurality of apertures aligned with each other in a direction transverse to the flat sides, to form a plurality of examination windows, in which the outer sides of the membranes are exposed.

Claims

1. A sample cell comprising: at least one sample space, which is restricted on its first flat side by a first inner side of a first membrane and on its second flat side by a second inner side of a second membrane, a spacer arranged between the first and the second inner sides, the spacer establishing a distance between the first and second membranes, a first retaining element arranged on a first outer side, which faces away from the at least one sample space of the first membrane, and a second retaining element arranged on a second outer side, which faces away from the at least one sample space of the second membrane, wherein the first and second retaining elements together form a retaining structure, the first and second retaining elements each have a plurality of apertures which are arranged to align with each other in a direction transverse to the first and second flat sides so that a plurality of examination windows are formed, in which the first and second outer sides of the first and second membranes are exposed.

2. The sample cell according to claim 1, wherein one or more of the first inner side of the first membrane is connected to the spacer, the first outer side of the first membrane is connected to the first retaining element, the second inner side of the second membrane is connected to the spacer, and the second outer side of the second membrane is connected to the second retaining element in a firmly bonded manner

3. The sample cell according to claim 1, wherein the firmly bonded manner is vacuum-tight.

4. The sample cell according to claim 1, further comprising a seal, which extends between the first inner side of the first membrane and the second inner side of the second membrane, in an edge region and seals off the at least one sample space from an outer space, wherein the seal comprises at least one access opening, through which the at least one sample space can be filled.

5. The sample cell according to claim 1, wherein the spacer, when viewed in a direction transverse to the first and second flat sides, has a constant material thickness so that the first and second inner sides of the first and second membranes are arranged at least approximately plane-parallel to each other.

6. The sample cell according to claim 1, wherein the at least one sample space has an aspect ratio between a lateral extent, measured in a direction at least approximately parallel to the first and second flat sides, and a thickness, measured in the direction at least approximately perpendicular to the first and second flat sides, of ten to one or greater.

7. The sample cell according to claim 1, wherein the at least one sample space has lateral extents, measured in a direction at least approximately parallel to the first and second flat sides, between 100 μm and 100 mm and the at least one sample space has a thickness, measured in the direction at least approximately perpendicular to the first and second flat sides, between 1 nm and 10 μm.

8. The sample cell according to claim 1, wherein the plurality of examination windows have a lateral dimension, viewed in a direction at least approximately parallel to the first and second flat sides, which is between 10 μm and 200 μm.

9. A loading station for receiving at least one sample cell according to claim 1, comprising a preparation reservoir and a sample cell holder, wherein the preparation reservoir is arranged geodetically deeper than the sample cell holder, is the sample cell holder being configured to receive the sample cell such that a fluid contact can be established between a subregion of the sample cell and the preparation reservoir.

10. The loading station according to claim 9 wherein: the at least one sample cell further comprising a seal, which extends between the first inner side of the first membrane and the second inner side of the second membrane, in an edge region and seals off the at least one sample space from an outer space, wherein the seal comprises at least one access opening, through which the at least one sample space can be filled; and the sample cell holder is configured to receive the at least one sample cell such that a fluid contact can be established between the at least one access opening and the preparation reservoir.

11. A measuring device for examining a sample which is present in the at least one sample space of the at least one sample cell according to claim 1, further comprising a radiation source which emits a measurement beam which is aimed at a subregion of the at least one sample cell, and a detector for detecting a measurement.

12. The measuring device according to claim 11, wherein the detector is configured to measure an electron diffraction image.

13. A method for examining a sample, comprising: providing a sample cell according to claim 1, introducing a sample solution or suspension into the at least one sample space of the sample cell, introducing the sample cell, which comprises the sample in the at least one sample space, into a measuring device comprising a radiation source which emits a measurement beam, aligning the sample cell in relation to the measurement beam so that the beam irradiates at least a part of the sample which is present in a subregion of the sample space of the sample cell, and recording a measurement of the sample.

14. The method according to claim 13, wherein the radiation source is an electron source.

15. The method according to claim 13, wherein the recorded measurement is an electron diffraction image.

16. The method according to claim 13, further comprising introducing a crystallizable sample solution into the at least one sample space of the sample cell, and subsequent to the introducing of the crystallizable sample solution into the at least one sample space, introducing the filled sample cell into a crystallization space and providing ambient conditions in the crystallization space that are favorable for crystal formation in the crystallizable sample solution.

17. A method for producing a flat crystal, comprising: providing a sample cell according to claim 1, introducing a crystallizable sample solution into the at least one sample space of the sample cell, introducing the filled sample cell into a crystallization space and providing ambient conditions in the crystallization space that are favorable for crystal formation in the crystallizable sample solution, after the crystal has formed in the sample space, removing one or more of the first and the second membranes and a corresponding one of the first and second retaining elements, and removing the crystal from the opened sample space.

18. The method according to claim 17, wherein the flat crystal is a monocrystal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Further features will become evident from the description of embodiments, together with the claims and the appended drawings. Embodiments can fulfill individual features or a combination of several features.

[0059] The embodiments are described below, without restricting the general idea of the invention, based on exemplary embodiments in reference to the drawings, whereby we expressly refer to the drawings with regard to the disclosure of all details that are not explained in greater detail in the text. In the drawings:

[0060] FIG. 1 illustrates a schematically simplified cross-section through a sample cell,

[0061] FIG. 2 illustrates shows a schematically simplified plan view of a sample cell,

[0062] FIG. 3 illustrates a schematically simplified detailed view of the sample cell shown in the plan view in FIG. 2,

[0063] FIG. 4 illustrates a schematically simplified perspective diagram of a loading station for receiving a sample cell,

[0064] FIG. 5 illustrates a schematically simplified side view of a loading station with a sample cell inserted, and

[0065] FIG. 6 illustrates a measuring device for examining a sample which is present in the sample space of a sample cell in a very simplified and schematic diagram.

[0066] In the drawings, the same or similar elements and/or parts are, in each case, provided with the same reference numerals such that they are not introduced again in each case.

DETAILED DESCRIPTION

[0067] FIG. 1 shows a schematically simplified section view of a sample cell 2 which comprises a flat sample space 4. In the diagram from FIG. 1, the sample cell 2 comprises, by way of example, a single sample space 4. According to further exemplary embodiments not shown in the figures, the sample cell 2 comprises more than one single sample space 4. In the context of the following description, reference is made to a sample cell 2 which has a single sample space 4 simply by way of example. The flat sample space 4 is restricted on its first large flat side 6a by a first inner side 8a of a first membrane 10a. On its second large flat side 6b, the sample space 4 is restricted by a second inner side 8b of a second membrane 10b. A spacer 12 extends between the first inner side 8a and the second inner side 8b, which spacer is built from multiple spacing elements 14 in the exemplary embodiment shown. In other words, the spacing elements 14 together form the spacer 12. The spacer 12 defines a distance d between the first membrane 10a and the second membrane 10b.

[0068] A first retaining element 18a is arranged on a first outer side 16a, which faces away from the sample space 4, of the first membrane 10a. A second retaining element 18b is arranged on a second outer side 16b, which also faces away from the sample space 4, of the second membrane 10b. The first retaining element 18a and the second retaining element 18b together form a retaining structure 20 of the sample cell 2. This retaining structure 20 is configured, for example, so that the sample cell 2 is inherently stable.

[0069] The first retaining element 18a and the second retaining element 18b each comprise a plurality of apertures 22. For reasons of simplicity, only one aperture 22 in each retaining element 18a, 18b is provided with a reference sign. The apertures 22 of the first and second retaining elements 18a, 18b are arranged to align with each other in a direction R transverse to the flat sides 6a, 6b. This results in a plurality of examination windows 24, in which the outer sides 16a, 16b of the membranes 10a, 10b are exposed.

[0070] In the region of the examination window 24, the sample cell 2 can be easily irradiated. This serves to examine a sample 26, which is present in the sample space 4 and only indicated in regions by hatching and which is, for example, a crystal, further, for example, a monocrystal. The sample cell 2 has particular utility for the examination of the sample 26 by electron diffractometry. The sample cell 2 is also suitable for examining the sample 26 by electromagnetic radiation, for example X-rays. In the region of the examination windows 24, the sample 26 is separated from the outer space only by the membranes 10a, 10b. For the membranes 10a, 10b, a material is selected that is largely transparent for the electromagnetic radiation used or respectively electron-transparent. If the measurement is performed by electron radiation, graphene, boron nitride, or the like, for example, are suitable as the material for the membranes 10a, 10b. The sample cell 2 has a plurality of examination windows 24. This has particular utility for an examination of the sample 26 with a high dose of radiation. The dose of radiation can be distributed over a large sample volume in that individual examination windows 24 are irradiated, for example, temporally one after another and the sample 26 is measured in this region. Radiation damage to the sample 26 can be reduced in this way.

[0071] Examinations by electron diffractometry take place in many cases under vacuum conditions. But not every sample 26 can be readily exposed to a vacuum. For this reason, the sample cell 2 according to one exemplary embodiment is configured to be vacuum-tight. To achieve this, the first inner side 8a of the first membrane 10a is connected in a firmly bonded manner to the spacer 12, at least to a part of the spacing elements 14 forming the spacer 12. The second inner side 8b of the second membrane 10b is also connected in a firmly bonded manner to the spacer 12, at least to a part of the spacing elements 14 forming the spacer 12. To improve the stability of the sample cell 2, the first outer side 16a of the first membrane 10a can also be connected in a firmly bonded manner to the first retaining element 18a. This also applies to the second retaining element 18b, which can be connected in a firmly bonded manner to the second outer side 16b of the second membrane 10b. A firmly bonded connection is achieved, for example, by applying a suitable pressure to the involved elements. The firmly bonded connection can take place without auxiliary substances or using one or more auxiliary substances. An auxiliary substance-free connection takes place, for example, by at least low interdiffusion of the materials into each other or by form-fitting adaptation at the microscopic level. Auxiliary substances that are suitable for producing a firmly bonded connection are, for example, vacuum-resistant adhesives, such as epoxy resins or the like.

[0072] FIG. 2 shows a schematically simplified plan view of a sample cell 2 according to another exemplary embodiment. The sample cell 2 comprises a sealing element 28, which is configured in two pieces and fulfills the function of a spacing element 14. Another spacing element 14 is arranged centrally in the sample space 4. This is surrounded by the sealing element 28. The sealing element 28 extends, just like it is shown in FIG. 1 for the spacing elements 14, between the first inner side 8a of the first membrane 10a and the second inner side 8b of the second membrane 10b. The sealing element 28 is arranged in an edge region of the sample cell 2 and seals off the sample space 4 from the outer space. In the exemplary embodiment shown, the sealing element 28 leaves the access openings 30 free, through which the sample space 4 can be filled.

[0073] In the plan view from FIG. 2, only the first retaining element 18a is visible. It is shown partially transparently with respect to the sealing element 28 and the central spacing element 14 which are below it. The apertures 22, which expose the examination windows 24, are located in the first retaining element 18a, arranged in a regular grid. The apertures 22 are indicated with dots in the subregions of the first retaining element 18a. The access openings 30 of the sealing element 28 can be closed in a vacuum-tight manner For this purpose, the access opening 30 is closed, for example, with a vacuum-resistant adhesive or another suitable sealant.

[0074] The detailed view shown in FIG. 3 in turn shows a plan view of the first retaining element 18a. This is built from webs 32 (cf. also FIG. 1), toward the upper end face 34 of which the view is directed in FIG. 3. The first retaining element 18a is produced, for example, from silicon. The apertures 22, of which only a single one is provided with a reference sign in FIG. 3, are produced, for example, by photolithography. Due to this production method, the typical structure of the webs 32, which is trapezoidal in cross-section, shown in FIG. 1 results. The flanks 36 of the webs 32 are shown in FIG. 3 with dotted shading.

[0075] The sample cell 2 according to the exemplary embodiments shown is provided with spacers or respectively spacing elements 14 which, viewed in a direction R transverse to the large flat sides 6a, 6b of the sample space 4, have an at least approximately identical material thickness. In other words, all of the spacing elements 14 forming the spacers 12 (the same also applies to the sealing element 28, if this forms part of the spacer 12) are configured with a constant identical material thickness. The spacer 12 defines the distance d between the inner sides 8a, 8b of the membranes 10a, 10b and thus a thickness of the sample 26, which is, for example, a crystal, further, for example, a monocrystal. The constant material thickness of the spacing elements 14 leads to the inner sides 8a, 8b of the membranes 10a, 10b being arranged at least approximately plane-parallel to each other. This in turn leads to a crystal present in the sample space 4 growing flat and having a very homogeneous thickness.

[0076] To provide a crystal, such as a monocrystal, as a sample 26 in the sample space 4, a crystallizable solution, for example, is introduced into the sample space 4 through the access openings 30. The crystallizable solution crystallizes within the sample space 4, for example, to form a monocrystal, which can then be examined by X-ray diffractometry.

[0077] A sample cell 2 according to further exemplary embodiments comprises a sample space 4, the aspect ratio of which between a lateral extent L, measured in a direction at least approximately parallel to the large flat sides 6a, 6b, and thickness that corresponds to the distance d of the membranes 10a, 10b, meaning is measured in the direction R at least approximately perpendicular to the large flat sides 6a, 6b, is in a ratio of at least 10:1. In other words, the sample space 4 is at least ten times as large in the lateral direction as in the direction perpendicular thereto in which it is irradiated. In a sample cell 2 which comprises, as shown in FIG. 2 by way of example, a square sample space 4, the lateral extent L is measured as an edge length.

[0078] The sample space 4 has a lateral extent L which is between 100 μm and 100 mm. A thickness of the sample space 4 is between 1 nm and 10 μm. The examination windows 24 have a lateral dimension L′, which is measured just like the lateral extent L of the sample space 4, which is between 50 μm and 200 μm in a direction at least approximately parallel to the large flat sides 6a, 6b. The lateral dimension L′ of the examination windows 24 is also measured as an edge length, if they are, as in the exemplary embodiment in FIG. 3, square examination windows 24 by way of example. Otherwise, what has been said regarding the dimension of the sample space 4 applies.

[0079] FIG. 4 shows a schematically simplified perspective diagram of a loading station 40 which is configured to receive at least one sample cell 2 according to one or more of the previously mentioned exemplary embodiments. The loading station 40 comprises a preparation reservoir 42, which is provided as a recess in the loading station 40, which is configured as a block. The walls of the preparation reservoir 42 form a sample cell holder 44 in portions. For example, the lateral end faces 46 of the projections 48 form the sample cell holder 44 in the exemplary embodiment shown in FIG. 4. The preparation reservoir 42 is arranged geodetically deeper than the sample cell holder 44. The sample cell holder 44 is also configured to receive the sample cell 2 such that a fluid contact can be established between a subregion of the sample cell 2 and the preparation reservoir 42.

[0080] FIG. 5 shows a very schematically simplified side view of the loading station 40 with a sample cell 2 placed therein. By way of example, a sample solution 50 or a suspension, such as a crystallizable sample solution 50 or suspension, is located in the preparation reservoir 42. It is also provided that the sample solution 50 or suspension is produced directly in the preparation reservoir 42. The sample cell holder 44 is configured to receive the sample cell 2 such that a fluid contact can be established between its access opening 30 and the preparation reservoir 42, or respectively the sample solution 50 present in the preparation reservoir 42. For this purpose, the sample cell 2 is submerged into the preparation reservoir 42 until the access opening 30 of the sample cell 2 is in fluid contact with the sample solution 50.

[0081] The sample solution 50 is sucked into the sample space 4 against the effect of gravity by capillary forces. After the sample cell 2 is loaded, the access opening 30 can be closed. If an examination of the sample 26 takes place immediately, it is not necessary to hold the sample 26 stable over a longer time and the access opening 30 does not have to be closed.

[0082] FIG. 6 shows a very schematically simplified diagram of a measuring device 60 for examining a sample 26 which is present in the sample space 4 of a sample cell 2 according to an exemplary embodiment. The measuring device 60 comprises a radiation source 62, which emits a measurement beam 64. The radiation source 62 is, for example, an electromagnetic radiation source, such as an X-ray source, or also an electron beam radiation source. The measurement beam 64 is aimed at a subregion of the sample cell 2 and strikes it in the region of an examination window 24. The measuring device 60 also comprises a detector 66, which is configured to detect measurement data, such as to detect an electron diffraction image or an X-ray diffraction image. To examine various examination windows 24 of the sample cell 2, the sample cell is arranged on a movable sample holder 68, for example a positioning table.

[0083] X-ray and electron detectors for measuring a diffraction image are well-known in the art. However, by way of example, the detector 66 can be a solid state detector that uses semiconductors to detect x-rays or electrons. There are direct digital detectors, so-called because they directly convert x-ray photons to electrical charge and thus a digital image. The detection of electrons directly provides an electrical charge and thereby the digital image. Furthermore, there are indirect systems that may have intervening steps. For example, first converting x-ray photons to visible light, and then an electronic signal. Both systems typically use thin film transistors to read out and convert the electronic signal to a digital image. The most simple and traditional detector is the chemical film, in which the silver-containing grains are directly affected by the x-rays and electrons, respectively.

[0084] The measuring device 60 also comprises a processing unit (e.g., processor, controller, CPU, PC computer etc.) 70, which is configured to move the sample holder 68 such that the sample 26, which is located within the sample space 4 of the sample cell 2, is measured at different regions in one examination window 24 of the sample cell 2 in each case by the measurement beam 64. The processing unit 70 can be configured to move the sample holder 68 such that the measurement beam 64 strikes different examination windows 24 of the sample cell 2 one after another. For this purpose, the processing unit 70, which also serves to read out the detector 66, is connected to the aforementioned units via suitable data connections 72. According to one exemplary embodiment, a method for examining a flat crystal which is present, for example, as a sample 26 in the sample space 4 of the sample cell 2 comprises the following.

[0085] First, a sample cell 2 according to an exemplary embodiment is provided. A crystallizable sample solution 50, a suspension, for example a liquid with crystals or crystallites contained therein or a sample present in liquid form in another way is introduced into the sample space 4 of the sample cell 2; this takes place, for example, using the loading station 40. If a crystallizable liquid is introduced into the sample cell 2, the filled sample cell 2 is subjected in a crystallization space to ambient conditions that are favorable for crystal formation of the crystallizable sample solution 50. Ambient conditions that are favorable for the crystallization process are, for example, certain temperatures or certain humidities. It is also provided that the sample cell 2 is only subjected to the usual ambient conditions/laboratory conditions if these are sufficient for crystal formation. In this case, the laboratory space corresponds to the crystallization space. Then the sample cell 2, which now comprises at least one crystal, for example a monocrystal, in its sample space 4, is introduced into a measuring device 60, which comprises a radiation source 62 that emits a measurement beam 64. As already previously explained multiple times, the radiation source 62 is, for example, an X-ray source or an electron radiation source. The sample cell 2 is aligned in relation to the measurement beam 64; this takes place, for example, using the sample holder 68. The alignment takes place such that one subregion of the sample cell 2 is irradiated in each case and an electron diffraction image, for example, can be recorded using a detector 66. The sample cell 2 is irradiated in the region of its examination windows 24.

[0086] According to one exemplary embodiment, a method for producing a flat crystal, such as a monocrystal, which can also be examined in a measuring device 60, as shown schematically simplified in FIG. 6, but also in another suitable measuring device, comprises the following.

[0087] Again, a sample cell 2 according to an exemplary embodiment is first provided. A crystallizable sample solution 50 is again introduced into the sample space 4 of the sample cell 2. The filled sample cell 2 is again held for a sufficient period of time in a crystallization space under ambient conditions that are favorable for crystal formation of the crystallizable sample solution 50. After a crystal, for example a monocrystal, has formed in the sample space 4 of the sample cell 2, the first membrane 10a including the first retaining element 18a and/or the second membrane 10b including the second retaining element 18b is removed. In this way, the sample space 4 is opened. The crystal, for example a monocrystal, present in the sample space 4 can be examined in the half-opened sample cell 2. It is also provided to remove the monocrystal present in the sample space 4 and supply it to a measurement. It is also provided to examine the crystal, held only by the sealing element 28, for example in transmission, after removing the membranes 10a, 10b on both sides including the retaining elements 18a, 18b.

[0088] The sample cell 2 can thus be used to grow a flat crystal, such as a monocrystal, in the sample space 4.

[0089] While there has been shown and described what is considered to be embodiments of the invention, it will, of course, be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the invention. It is therefore intended that the invention be not limited to the exact forms described and illustrated, but should be constructed to cover all modifications that may fall within the scope of the appended claims.

[0090] List of Reference Signs

[0091] 2 Sample cell

[0092] 4 Sample space

[0093] 6a First large flat side

[0094] 6b Second large flat side

[0095] 8a First inner side

[0096] 8b Second inner side

[0097] 10a First membrane

[0098] 10b Second membrane

[0099] 12 Spacer

[0100] 14 Spacing element

[0101] 16a First outer side

[0102] 16b Second outer side

[0103] 18a First retaining element

[0104] 18b Second retaining element

[0105] 20 Retaining structure

[0106] 22 Aperture

[0107] 24 Examination window

[0108] 26 Sample

[0109] 28 Sealing element

[0110] 30 Access opening

[0111] 32 Web

[0112] 34 End faces

[0113] 36 Flanks

[0114] 40 Loading station

[0115] 42 Preparation reservoir

[0116] 44 Sample cell holder

[0117] 46 Lateral end faces

[0118] 48 Projections

[0119] 50 Sample solution

[0120] 60 Measuring device

[0121] 62 Radiation source

[0122] 64 Measurement beam

[0123] 66 Detector

[0124] 68 Sample holder

[0125] 70 Processing unit

[0126] 72 Data connections

[0127] d Distance

[0128] L Lateral extent

[0129] L′ Lateral dimension

[0130] R Direction