US3714426A

US3714426A - Method of x-ray analysis of crystal structure an x-ray goniometer for carrying out said method

Info

Publication number: US3714426A
Application number: US00119102A
Authority: US
Inventors: E Wolfel; R Wendel
Original assignee: STOE AND CIE GmbH
Current assignee: STOE AND CIE GmbH
Priority date: 1970-08-18
Filing date: 1971-02-26
Publication date: 1973-01-30
Anticipated expiration: 1990-01-30
Also published as: DE2041031A1; DE2041031B2; GB1343529A

Abstract

A method and apparatus of photographing the reciprocal crystal lattice in the structural analysis of crystals by means of sharply concentrated monochromatic X-rays, using an X-ray goniometer having a rotatably mounted crystal and a film which can, if necessary, be rotated in its plane and in front of which a shutter is arranged. The film is supported parallel to the rotational axis of the crystal for producing diffraction images in accordance with the Buerger procession principle and in a normal position relative to the rotational axis for producing diffraction images in accordance with the de-Jong-Bouman method. In the latter case, the rotational axis of the crystal is pivoted and rotated together with the rotational axis of the film and parallel thereto through an angle of at the most, 45* to the direction of the X-ray beam.

Description

lnventors: Erich R. Wolfel, Darmstadt; Richard H. Wendel, Reinheim, both of Germany Stoe & Cie, Gmbll, Darmstadt, Germany Filed: Feb. 26, 1971 Appl. No.: 119,102

Assignee:

Field of Search ..250/5l.5, 52, 54, 55, 58, 68; 33/69, 72; 356/30, 31

References Cited UNITED STATES PATENTS 1/1958 Bond ..250/5 1 .5

10/1963 Buerger ..250/51.5

United States Patent 1 1 3,714,426 Wolfel et al. 1 Jan. 30, 19 73 1541 METHOD OF X-RAY ANALYSIS OF 3,394,255 7/1968 Furnas, Jr ..250/51.5 CRYSTAL STRUCTURE AN X-RAY 3,466,438 9/1968 Abrahamsson ..250/51.5

3,546,453 12/1970 a t 1. ..250/515 ggg gggggg w 5,.91. Haiti's:

Primary Examiner--David Schonbcrg Assistant Examiner-Paul R. Miller Attorney-Woodhams, Blanchard & Flynn [57] ABSTRACT tion images in accordance with the Buerger procession principle and in a normal position relative to the rotational axis for producing diffraction images in accordance with the de-Jong-Bouman method. In the latter case, the rotational axis of the crystal is pivoted and rotated together with the rotational axis of the film and parallel thereto through an angle of at the most, 45 to the direction of the X-ray beam.

25 Claims, 4 Drawing Figures METHOD OF X-RAY ANALYSIS OF CRYSTAL STRUCTURE AN X-RAY GONIOMETER FOR CARRYING OUT SAIDMETHOD The present invention relates to a method ofX-ray analysis of crystal structure and to an X-ray goniometer for carrying out said method.

There are known methods and apparatus for analyzing the structure of crystalline substances by means of X-rays. To interpret the Bragg-reflections which occur during X-ray diffractions in a crystal, special use is made of photographic recordings of the reciprocal crystal lattice, which are made by rotating the crystal with the aid of the Weissenberg goniometer and the Buerger precession goniometer. Both instruments are commonly used and permit the taking of complementary photographs, the reflections of which being arranged in layer lines not only give information as to the quality and the symmetrical properties of the crystal under analysis, but also make it possible to determine its space-group in the crystallographic system as well as the lattice constants.

One particular disadvantage of the conventional mode of operation resides in the fact that there must always be provided two instruments for the complete interpretation or determination of space-groups. With the Weissenberg goniometer distorted photographs can be taken of the reciprocal lattice planes perpendicular to the axis of rotation, whereas the Buerger goniometer produces undistorted photographs of reciprocal lattice planes parallel to the rotational axis of the crystal. Apparatus has been provided which only requires the transference of the goniometer head and the already adjusted crystal from one instrument to the other, but re-location of the crystal is sometimes unavoidable in this connection. Furthermore, not only is expenditure high in respect of the instruments, but also interpretation is rendered more difficult and therefore time-consuming owing to the photographs being fundamentally dissimilar. An average of one to two weeks is required for gaining complete and sufficiently accurate data on a single crystal. Details of these methods and apparatus can be found for example in the publications of MJ. Buerger, X-Ray Crystallography, New York 1942, and The Precession Method in X-Ray Crystallography" New York 1964.

ln addition, a so-called Rimsky retigraph has been proposed, with which undistorted photographs of reciprocal lattice planes can be taken perpendicular to the axis of rotation, but this apparatus has not had any practical success owing to its relatively complicated structure. A description of this arrangement is contained in a brochure of Hilger & Watts Ltd, London published in April 1957.

The main object of the invention is to provide a method and apparatus for the X-ray analysis of crystal structure, in which all the photographic recordings necessary for determining space-groups can be made rapidly and with the minimum of expenditure on apparatus and can be simply and sufficiently accurately interpreted.

The invention is based on a method for producing photographs of the reciprocal lattice during the structural analysis of crystals with sharp beams of monochromatic Xrays by the use of an X-ray goniometer having a rotatably mounted crystal, a flat film which can if necessary be rotated in its plane and a pre-set diaphragm, and provides that the film for producing diffraction images parallel to the rotational axis of the crystal in accordance with the Buerger precession method and for producing diffraction images accordingto the de-Jong-Bouman method is supported in itsnormal position relative to the rotational axis of the crystal, and in the latter case, the rotational axis of the crystal together with and parallel to the rotational axis of the film is pivoted and rotated through an angle of at the most, 45 to the direction of the X-ray beams.

A preferred embodiment of this method is provided in accordance with the invention in that the distance between the plane of the film and the crystal can be selected in such a manner that the image scale is the same for all photographs.

The advantages and possible applications of the Buerger precession goniometers and a de-Jong-Bouman goniometer are combined in the invention. In this connection the same circular film cassette can be used to obtain photographs of the reciprocal lattice planes both perpendicular and parallel to the rotational axis of the crystal. it is sufficient, using the same apparatus, to bring the film-cassette and its holder into one position parallel, and the second time into a position perpendicular to the rotational axis of the crystal. In this case, re-orientation of the crystal is not necessary. By simply adjusting the distance between the plane of the film and the crystal an undistorted image is obtained, whereupon interpretation is considerably'simplified and accelerated.

In an X-ray goniometer having a primary beam collimator and a pivoting unit, the angular position of which can be varied and which is guided in the opposite direction to that of the X-ray which is fixed by said collimator. Said pivoting unit supporting a rotatable holder for a crystal, a film cassette located some distance therefrom and an optical system, which is if necessary removable, for checking the adjustment of the crystal and being in the form of a linked parallelogram which can be pivoted in its plane by means of a wobble drive. It is provided in accordance with the invention that the wobble drive which can be disengaged in a manner known per se can be fixed parallel to the pivoting plane, that the adjustable pivoting unit supports two devices, which normally are arranged facing one another for receiving the re-locating unit comprising a film cassette and a distance-setting arrangement, and that the film cassette in one receiving device can be rotated synchronously with the crystal about an axis parallel to the rotational axis of the crystal.

The invention is furthermore directed towards an X- ray goniometer with a housing which comprises holders for a primary beam collimator and a primary beam collector for at least one drive motor as well as bearings for an oscillating mechanism which is drivably connected to the latter and for two horizontal rails which are arranged at a fixed distance from and parallel to one another and can each be pivoted about a vertical axis, the first track carrying a rotatable crystal holder and, opposite this, an optical system for checking the adjustment ofa crystal to be analyzed, while the second rail supports a carrier which is connected to the oscillating mechanism comprising an angularly adjustable segment and a rotating axle which can be alternatively coupled with the motor and lies parallel to the axis of the collimator, said rails being connected by two guide means to form a linked parallelogram, as well as a film cassette which is coordinated with a shutter at a variable distance. In an apparatus of this type the invention provides a carrier in the form of a half bent portion which on the segment side supports a first receiving device which is identical to a second receiving device mounted on the second rail opposite the fastening point of the carrier, and the film cassette together with a distance-setting arrangement which can be alternately mounted on one or the other receiving device in front of which is arranged an associated shutter.

Other features, details and advantages of the invention are seen in the following description of preferred embodiments with the aid of the drawings.

FIG. 1 shows a diagrammatic plan view of an X-ray goniometer according to the invention for producing photographic diffraction images in accordance with the Buerger precession method,

FIG. 2 shows a diagrammatic plan view of an X-ray goniometer according to the invention for producing photographic diffraction images in accordance with the de .long-Bouman rotation method,

FIG. 3 shows a diagrammatic axial section through a couplingof the apparatus shown in FIGS. 1 and 2, and

FIG. 4 shows an extended cross-section of an apparatus for receiving a unit consisting of a film cassette and a setting device.

CONSTRUCTION The principle of the structure of an apparatus according to the invention can be seen in FIGS. I and 2, The apparatus is provided with a lightweight metal housing which is supported on vertically adjustable feet (not shown) and the interior of which contains electrical components for controlling the operation, particularly also a set of push buttons 43 and the associated wiring having a mains connection. On one side the housing has a supporting arm 11 into which can be inserted a primary beam collimator of given diameter. A conventional primary beam collector I3 is attached to the same supporting arm 11. Opposite the supporting arm 11 the housing 10 is provided with a support 14 for supporting a drive motor 15 having a connection 16 leading to a rotating axle 26 which runs parallel to the axis of the collimator 12. The apparatus is arranged so that the longitudinal axis which is formed by the collimator axis and the rotational axis 26 coincides with the X-ray beam X during the entire operation.

The apparatus according to the invention is similar in construction to a Buerger precession goniometer. Mounted on the housing l0 at a predetermined distance E therefor are two pivot bearings 19,20 in which

rails

21 and 22, respectively, are pivotally mounted. These two

rails

21,22 are connected by

guides

27,28 to form a linked parallelogram comprising links or

connections

40a, 40b, 40c and 40d. The pivoting axles lie in the same plane as the axis of the collimator or the incident X-ray beam X. Whereas a Buerger precession goniometer of the conventional type makes use of a wobble drive provided with a joint having two degrees of freedom in the manner of a universal joint which is connected to either side of the second rail 22,

the corresponding wobble drive in the invention is only provided with a universal joint on one side so that the unoccupied space is used to install other elements provided in accordance with the invention.

The first rail 21 which is adjacent to the collimator 12 supports a rotatable crystal holder 18 which is connected to a graduated scale drum 35 for setting a given angle of rotation and to drive motor 38. The crystal K is mounted on the rotating axle A which is supported by the holder 18. Its adjustment can be monitored by means of a microscope/telescope system 23 which is secured on the first rail 21 opposite the motor 38. The end of the second rail 22 adjacent to the motor 38 supports a bracket 32 for securing a half bent carrier 31. It is connected by a rotatable bearing 17 to a segment 25 in which a short bent sliding piece 25a can be slidably moved through the groove of a bent guide piece 25d having the same radius of curvature.

On the side facing the second rail 22, the carrier 31 supports a device B for receiving a re-setting unit U which consists of a film cassette 29 connected to a distance setting arrangement 33. A similar receivingdevice J is mounted on the second rail 22 opposite the bracket 32 above the joint 40d. This second receiving device .I is drivably connected to a motor 41 which can be moved synchronously with the motor 38 so that the rotational axis A of the crystal and the rotational axis G of the film (FIG. 2) can rotate parallel to one another at the same speed and in the same direction.

FIG. 3 shows details of the mechanical arrangement whereby the apparatus according to the invention can be driven or stopped in the required manner when changing the method of operation described below. For this purpose a graduated drum 35 is provided with a coupling 37 with which the rotatable crystal holder 18 can be alternately moved into a driving connection with a motor 38 (position D) brought into the idling position (position 0) or stopped (position 8). I

The connection 37 is in the form of a screw having a knurled head which can be screwed back and forth in a sleeve 68 having a relatively sharp thread. The shank 67 of this screw 37 is provided with two conical faces 53,60 which are separated by a cylindrical central portion 58 and are directed away from one another. The central portion 58 is supported in the 0 position between two pins 61,62 which are radially movable relative to the shank 67 and one of which can be raised from the associated

conical face

59 or 60 during the axial movement of the screw 37 through the sleeve 68. The pins 61,62 are slidably guided in the sleeve 68 for this purpose. When in the B position one pin 61 (on the left hand side in FIG. 3) is brought into contact with a rigid portion 63 of the illustrated arrangement. This setting can be selected for producing diffraction images in accordance with the Buerger precession method. In the D position the other pin 62 (on the right hand in FIG. 3) is brought into contact with an inner face of a driver wheel 64 which is'connected to the motor 38 via a belt drive 65. This position is required for the apparatus to be ready to produce diffraction images in accordance with the de-Jong-Bouman method. Neither of the pins 61,62 is raised in the intermediate position 0 so that the crystal holder 18 is freely rotatable. This position is required for adjusting the crystal K which is supported on a goniometer head (not shown).

FIG. 4 shows an exploded cross-section through individual parts of a reversing unit U. The film cassette 29 can be secured by means of a pin 36 in a holder 45 which in turn can be inserted into a telescoped section 46 and is held in the defined angular position by means of a pin. The telescoped section 46 is provided with a connecting channel 47 which is similar to a sharp threaded groove and in which a sliding piece 48 of a graduated adjusting ring 49 is slidably guided. The

latter is rotatably mounted on a distance-sleeve 70 which is accurately secured in its position relative to the other part by a centralizingplate 54 having an adjustable pin 53 and provided with an outer ring or collar 71. A screw cap 55 provided with a female thread 56 is used to firmly screw the entire reversible unit U onto the conical extensions 50 of the receiving devices B and .I which are provided with a male thread 51, depending on the selected method of operation.

Supported on the carrier 31 on the segment side is the device B for receiving the unit U consisting ofa film METHODS OF OPERATION When in the operative position shown in FIG. 1 the apparatus is used to produce diffraction images in accordance with the Buerger precession method. In this connection, a precession shutter 30 is arranged in front of the film cassette 29. The short sliding piece 25a in the guide portion 25b of the segment 25 can be adjusted by means of a set screw 39 through a predetermined angle of, e.g., 30 at the most, to the rotational axis 26 and therefore to the X-ray beam X. If, for example, an angle of inclination p. is set, the screw connection 16 is actuated and the drive motor together with the oscillating mechanism 24 causes the two

rails

21,22 to execute a pivoting movement parallel to one another through in opposite the direction of the X-ray beam X. The segments 25a and 25b are provided with graduated scales for the accurate setting of the angle of inclination p. The connection 16 can be in the form of a screw, the adjustment of which causes the drive motor 15 to be coupled to the gear drive.

When in the operative position shown in FIG. 2 the apparatus is used for producing diffraction images in accordance with the de-Jong-Bouman method. In this connection the unit U is transferred onto the second receiving device 1, the shutter 30 removed and a second shutter 34 arranged in front of the film cassette 29 coaxially to the rotational axis A ofthe crystal (FIG. 2). Since the receiving device J is exactly the same as the receiving device B, a precisely similar position of the unit U is fixed by the same fastening members. Also the film which lies in the same plane as the circular film cassette 29 and its equator are secured in a position relative to the X-ray X by means of a 3 hole arrangement. When the film is cut, the same three holes are used for securing.

The apparatus is advantageously adjusted so that, in order to operate with X-rays of a given constant wavelength, the film cassette 29 is precisely located in one end position for the 0 layer lines of Buerger photographs and in the other end position of the setting arrangement 33 for the 0 layer lines of de-Jong-Bouman photographs. For this purpose it can be provided with a graduated scale of e.g. 200 graduation marks for a setting distance of e.g. 20 mm so that one mark corresponds to 0.1 mm and a setting distance 0.05 mm can be safely estimated. Since the movement of the film is effected in the opposite direction from the said other end position (in the case of de-Jong-Bouman photographs), the setting distance must be subtracted or a scale running in the opposite direction must be provided. The speed of the rotating film cassette 29 and the crystal K is, for example, 1 rpm, whereas with photographs taken in accordance with the Buerger precession method the segment 25 rotates at an approximate speed of 2 rpm.

A cassette having a normal speed film can be replaced by a cassette for film which can be rapidly developed, e.g. a Polaroid XR-7 plane film cassette or an integrating mechanism.

The circular shutter 34 for taking photographs in layer lines in accordance with the de-Jong-Bouman method is supported parallel to the film cassette 29 and coaxial with the crystal K on the first rail 21 at a constant distance of e.g. 30 mm from the crystal K. it it is desired to produce diffraction images with higher layer lines in accordance with the de-Jong-Bouman method, the movement of the film V is first set before the pivoting angle p. on the segment 25 is determined. An adjustment in the reverse order would cause the shutter 34 to bear against the film cassette 29.

The optical system 23 comprising a microscope and telescope which are mounted opposite the crystal holder 18 is used to monitor the adjustment of a crystal. It contains a deflecting mirror which is mounted below the crystal and inclined at an angle of 45, whereby the crystal K can be accurately observed. The adjustment is particularly simple if the crystal Khas prismatic faces. The actual adjusting operation is effected by means ofa goniometer head which can be attached to the crystal holder 18 and provided with the usual adjusting means. Accuracy in adjustment is approximately plus or minus 0.l and can be considerably improved if the goniometer head has special guide means which ensure troublefree adjustment. The entire goniometer head can be axially moved by means ofa setting arrangement 44 in the direction of the rotational axis A of the crystal.

During photographing the collimator 12 which is directed towards the crystal K and the conventional primary beam collector 13 which is mounted in the same direction behind the crystal K give rise to a low degree of stray radiation and therefore maximum resolving power when optimum intensity is used. Different collimato rs can be used depending on the required sharpness of the beam, for example, those having an internal diameter of 0.3 mm, 0.5 mm or 0.8 mm and corresponding divergences of for example 0.2, 03 or 0.5". A V-way (not shown) in the supporting arm 11, together with the symmetrical design of the collimator 12 during rotation, simply ensure precise interchangeability so that a reproduceability of i0.l is ensured without any adjustment.

OPERATION The following steps or settings which originate from the basic apparatus are required for operating a goniometer in accordance with the Buerger precession method:

1. Adjusting the crystal K, the head of the screw 37 on the graduated drum 35 standing at zero;

2. Inserting the precession shutter 30 and setting its distance s relative to the crystal K;

3. Setting the angle of precession p. on the segment 4. Inserting the film cassette 29 in the receiving device B and setting the film distance V with the setting mechanism 33;

5. Turning the screw 37 on the graduated drum 35 to the B position;

6. Actuating the clutch 16 for the drive motor 15 and switching on said motor.

Also originating from a basic apparatus not yet in operation, the following steps or settings are required for using a goniometer in accordance with the de-Jong- Bouman method:

l. Adjusting the crystal K, the screw 37 on the graduated drum 35 being in the position;

2. inserting the de-Jong-Bouman shutter 34;

3. Setting the segment 25 at a pivoting angle a and fixing the segment in a horizontal position by means of an adjusting means which can be a block gauge, square or any other gauge and brings the segment into a precisely parallel position relative to the housing 4. inserting the film cassette 29 into the receiving device J and setting its spacing V by means of the setting mechanism 33;

5. Turning the screw head 37 on the graduated drum 35 to the D position;

6. Switching on both

motors

38 and 41 on the two

tracks

21 and 22, respectively.

If the apparatus had been previously operated in accordance with the Buerger precession method and was to be converted for operation according to the de-Jong- Bouman method, only the following steps are necessary:

1. Turning the screw head 37 on the graduated drum 35 to the D position;

2. Removing the precession shutter 30 and installing the de-Jong-Bouman shutter 34;

3. Fixing the segment 25 in a horizontal position and setting the pivoting angle (L;

4. Removing the unit U comprising the film cassette 29 and setting mechanism 33 from the receiving device 8 and inserting it into the receiving device .1 as well as setting the film distance V relative to the crystal K;

5. Switching on both

motors

38 and 41.

When the indicated steps are taken or settings made, photographs are then taken of the diffraction images produced by the X-ray beam X. lts interpretation is effected in the usual manner, as can be seen from, for example, the publications referred to at the beginning of the specification.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. A method for taking pictures of a three dimensional reciprocal lattice for the structural analysis of a crystal by applying the known Buerger precession principle and the known de-Jong-Bouman method and using a single X-ray goniometer, the steps com prising:

placing a first film on a rotatable support structure and in a position parallel to the rotational axis of said crystal; exposing said first film to an X-ray beam transmitted from said crystal to said first film to produce diffraction images according to the Buerger precession principle; rotating said support structure through an angle; placing a second film on said support structure in place of said first film and in a position normal to the rotational axis of said crystal; and then exposing said second film to an X-ray beam transmitted from said crystal to said second film to produce diffraction images according to the de- Jong-Bouman method.

2. A method according to claim 1, wherein said angle that said support structure is rotated is 45.

3. A method according to claim 1, including the step of adjusting the spacing between said crystal and one of said first and second films so that the image scale of the diffraction images is the same.

4. An X-ray goniometer, comprising:

means defining an X-ray beam path;

means defining a supporting member;

mounting means pivotally secured to said supporting member and pivotable between a first position and a second position, said mounting means including first holding means for holding a crystalline structure in the path of said X-ray beam path and second holding means for holding a film containing film cartridge in the path of said X-ray beam path in spaced relationship along said X-ray beam path from said crystalline structure, said crystalline structure and said film cartridge being pivotable upon a pivoting of said mounting means between said first position vwherein diffraction images are produced on the film in said film cartridge in accordance with the known Buerger precession principle and said second position wherein diffraction images are produced on the film in said film cartridge in accordance with the known de-Jong-Bouman method.

5. An X-ray goniometer according to claim 4, wherein said mounting means comprises a pair of pivotally supported and parallel rail members connected to each other through a pair of spaced guide members longitudinally spaced along said rail members and which are pivotally secured to said rail members whereby said pair of rail members and said pair of guide members define a parallelogram, said first holding means for holding a crystalline structure being mounted on one of said rail members and said film cartridge being mounted on the other of said rail members.

6. An X-ray goniometer according to claim 5, wherein said second holding means includes pivot means for pivotally supporting said film cartridge relative to said other of said rail members for adjustment relative to said X-ray beam path.

7. An X-ray goniometer according to claim 6, wherein the pivot axis for said pivot means is parallel to the pivot axis of said pivotally supported pair of rails.

8. An X-ray goniometer according to claim 7, including carrier means which comprises a guide portion mounted on said supporting member means, a sliding piece slidably mounted on said guide portion, a bracket secured to one of said parallel bars and said sliding piece, and adjustment means for adjusting the angular position of said parallel rails relative to said guide portion and said X-ray beam path.

9. An X-ray goniometer according to claim 8, wherein said adjustment means includes a set screw for locking and sliding piece to said guide portion.

' 10. An X-ray goniometer according to claim 8, including means defining a shutter positioned between said crystalline structure and said film cartridge.

11. An X-ray goniometer according to claim 10, wherein said shutter comprises a Buerger precession shutter when said mounting means is in said first position.

12. An X-ray goniometer according to claim 10, wherein said shutter comprises a de-Jong-Bouman shutter when said mounting means is in said second position.

13. An X-ray goniometer according to claim 8, including means for adjusting the relative distance between said crystalline structure and said film in said film cartridge, so that the diffraction images produced on the film in accordance with the Buerger precession principle and the de-Jong-Bouman method are the same scale.

14. An X-ray goniometer according .to claim 8, wherein said adjustment means includes an oscillating drive mechanism for oscillating said mounting means relative to said X-ray beam path.

15. In an X-ray goniometer having a housing which comprises holders for a primary beam collimator, a primary beam collector and at least one drive motor and an oscillating mechanism which is drivably connected to said drive motor and to a pair of horizontal rails which are arranged at a fixed distance from and parallel to each other and are connected by means of two guides to form a linked parallelogram, each of said pair of rails being pivotable about parallel axes, the first of said pair of rails supporting a rotatable crystal holder and an optical system for monitoring the adjustment of a crystal to be analyzed, the second of said rails including means for supporting a carrier connected to said oscillating mechanism which comprises an angularly adjustable segment and a rotating axle which can be selectively connected to the motor and is parallel with the axis of the collimator, and a film cassette which is associated with a shutter arrangement and means for varying the distance therebetween, wherein the improvement comprises said carrier includes means for supporting a first receiving device, a second receiving device mounted on said second rail remote from a bracket which is secured to said carrier, and a film cassette together with a distance setting mechanism being pivotally mounted on at least one of said first and second receiving devices in front of which is arranged an associated shutter mechanism.

16. An X-ray goniometer according to claim 15, wherein the segment consists of two parts which are slidably guided for movement along each other and has graduated scales thereon, which parts can be secured in a given angular position by means of a set screw, and

wherein the distance between and the dimensions of the elements or units arranged opposite one another on each of said pair of tails are selected so that at least an approximately static balance is achieved.

18. An X-ray goniometer according to claim 15, wherein said first receiving device is rigidly fastened to said carrier, andwherein said second receiving device on said second rail can be driven by means of a motor synchronously with and in the same direction as the rotational axis of the crystal.

19. An X-ray goniometer according to claim 15, wherein the distance setting mechanism is provided with a telescoped section which supports a holder for said film cassette, and a channel in the form of a threaded groove through which a slide piece connected to an adjusting ring is guided.

20. An X-ray goniometer according to claim 19, wherein tubular extensions having an external thread are provided for fastening said film cassette to said distance setting mechanism on one of said receiving devices and a screw cap having a corresponding internal thread being provided on said holder, and including a pin and a centralizing plate for one of the distance setting mechanism and the film cassette.

21. An X-ray goniometer according to claim 15, including a rotatable crystal holder a screw head for moving said crystal holder alternately into one of a driving connection with a motor (D), an idling position (position 0) and a stopped (position B).

22. An X-ray goniometer according to claim 21, wherein the shank of said screw head is provided with two conical surfaces which are divergent away from one another and separated by a cylindrical central portion, wherein said central portion in the 0 position is positioned between a pair of pins which are movable radially to the shank and of which one can be lifted from a conical face during the axial movement of the screw through the sleeve which supports said pins, and

wherein, when in the B position, a first of said pair of pins can be brought into contact with a rigid section and, when in the D position, a second of said pair of pins can be brought into contact with an inner face of a driver wheel which is drivably connected to said motor by a belt drive.

23. An X-ray goniometer according to claim 15, wherein the film cassette is provided with a three hole arrangement for securing the film, of which the equatorial plane relative to the X-ray beam is thereby defined.

24. An X-ray goniometer according to claim 15, including an optical system which comprises a telescope and microscope and which permits alternate distant and close observation of the crystal.

25. An X-ray goniometer according to claim 24,

wherein the crystal is mounted on a goniometer head, said goniometer head being provided with slidable guide means which are not subject to slackness or jerkiness and wherein said goniometer head can be moved by means of a second mechanism in the direction of the rotational axis of the crystal.

Claims

1. A method for taking pictures of a three dimensional reciprocal lattice for the structural analysis of a crystal by applying the known Buerger precession principle and the known deJong-Bouman method and using a single X-ray goniometer, the steps comprising: placing a first film on a rotatable support structure and in a position parallel to the rotational axis of said crystal; exposing said first film to an X-ray beam transmitted from said crystal to said first film to produce diffraction images according to the Buerger precession principle; rotating said support structure through an angle; placing a second film on said support structure in place of said first film and in a position normal to the rotational axis of said crystal; and then exposing said second film to an X-ray beam transmitted from said crystal to said second film to produce diffraction images according to the de-Jong-Bouman method.

1. A method for taking pictures of a three dimensional reciprocal lattice for the structural analysis of a crystal by applying the known Buerger precession principle and the known de-Jong-Bouman method and using a single X-ray goniometer, the steps comprising: placing a first film on a rotatable support structure and in a position parallel to the rotational axis of said crystal; exposing said first film to an X-ray beam transmitted from said crystal to said first film to produce diffraction images according to the Buerger precession principle; rotating said support structure through an angle; placing a second film on said support structure in place of said first film and in a position normal to the rotational axis of said crystal; and then exposing said second film to an X-ray beam transmitted from said crystal to said second film to produce diffraction images according to the de-Jong-Bouman method.

2. A method according to claim 1, wherein said angle that said support structure is rotated is 45*.

4. An X-ray goniometer, comprising: means defining an X-ray beam path; means defining a supporting member; mounting means pivotally secured to said supporting member and pivotable between a first position and a second position, said mounting means including first holding means for holding a crystalline structure in the path of said X-ray beam path and second holding means for holding a film containing film cartridge in the path of said X-ray beam path in spaced relationship along said X-ray beam path from said crystalline structure, said crystalline structure and said film cartridge being pivotable upon a pivoting of said mounting means between said first position wherein diffraction images are produced on the film in said film cartridge in accordance with the known Buerger precession principle and said second position wherein diffraction images are produced on the film in said film cartridge in accordance with the known de-Jong-Bouman method.

10. An X-ray goniometer according to claim 8, including means defining a shutter positioned between said crystalline structure and said film cartridge.

14. An X-ray goniometer according to claim 8, wherein said adjustment means includes an oscillating drive mechanism for oscillating said mounting means relative to said X-ray beam path.

16. An X-ray goniometer according to claim 15, wherein the segment consists of two parts which are slidably guided for movement along each other and has graduated scales thereon, which parts can be secured in a given angular position by means of a set screw, and wherein a first part is rotatably connected to said carrier by a rotatable bearing and the second part is rigidly connected to the rotating axle.

17. An X-ray goniometer according to claim 15, wherein the distance between and the dimensions of the elements or units arranged opposite one another on each of said pair of rails are selected so that At least an approximately static balance is achieved.

18. An X-ray goniometer according to claim 15, wherein said first receiving device is rigidly fastened to said carrier, and wherein said second receiving device on said second rail can be driven by means of a motor synchronously with and in the same direction as the rotational axis of the crystal.

21. An X-ray goniometer according to claim 15, including a rotatable crystal holder a screw head for moving said crystal holder alternately into one of a driving connection with a motor (D), an idling position (position O) and a stopped (position B).

22. An X-ray goniometer according to claim 21, wherein the shank of said screw head is provided with two conical surfaces which are divergent away from one another and separated by a cylindrical central portion, wherein said central portion in the O position is positioned between a pair of pins which are movable radially to the shank and of which one can be lifted from a conical face during the axial movement of the screw through the sleeve which supports said pins, and wherein, when in the B position, a first of said pair of pins can be brought into contact with a rigid section and, when in the D position, a second of said pair of pins can be brought into contact with an inner face of a driver wheel which is drivably connected to said motor by a belt drive.