Abstract:
An object of the invention is to provide an electron microscope which can easily and safely prepare a gas or liquid environment in the electron microscope and can observe a specimen in the environment and a reaction of the specimen at a high resolution and to provide a specimen holder for the electron microscope. In the electron microscope including specimen holding means ( 6 ) for holding a specimen ( 23 ), the specimen ( 23 ) is placed in a capillary ( 17 ) through which electron beams are transmittable, the electron microscope includes a supply device for supplying gas or liquid into the capillary ( 17 ) and a collection device for collecting the gas or the liquid, and the electron microscope obtains a specimen image of the specimen while flowing the gas or the liquid.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an electron microscope and a specimen holder included in the electron microscope. 
       BACKGROUND ART 
       [0002]    PTL 1 discloses an example where, by using, as a member for observing, in real time, a state in which a specimen is reacted with gas at a high temperature, an electron microscope or the like in which a specimen holder including a capillary tube for spraying gas toward a heater for heating the specimen is provided, such a gas reaction at the high temperature is observed. PTL 2 discloses an electron microscope in which gas is introduced in a horizontal direction, however, a specimen holder has openings for allowing electron beams to pass therethrough in a vertical direction. PTL 3 discloses an example where a capillary that can house a specimen has a rotation mechanism and is placed on a stage of the microscope. 
       CITATION LIST 
     Patent Literatures 
       [0003]    PTL 1: JP-A-2003-187735 
         [0004]    PTL 2: JP-A-51-267 
         [0005]    PTL 3: JP-A-10-206748 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0006]    In the conventional art described above, in a structure for introducing gas and liquid into cells between which a gas environment and a vacuum are separated by overlapping separating membranes, it is necessary to adhere cell parts or perform sealing with the use of a gasket or the like in order to prevent the gas and the liquid from leaking from the cells. Therefore, there is a problem that assembly of the cells and attachment thereof to a specimen support are complicated. Further, there is a problem that the gas and the liquid are leaked due to unsatisfactory sealing. 
         [0007]    In order to perform three-dimensional observation of a specimen under an optical microscope, the other conventional art described above discloses a method in which the specimen is placed in a capillary and is observed while being rotated. The other conventional art does not consider a case of using an electron microscope. Further, the other conventional art does not also consider a case where gas or liquid to react with the specimen is filled in the capillary or a case where the specimen in an environment of the gas or the liquid is heated and is superimposed with a voltage and a reaction thereof is observed. 
         [0008]    An object of the invention is to provide an electron microscope which can easily and safely prepare a gas or liquid environment or a gas-liquid mixed stream solution environment in the electron microscope and can observe a specimen in the environment and a reaction of the specimen at a high resolution and to provide a specimen holder for the electron microscope. 
       Solution to Problem 
       [0009]    In view of the problems, the invention has a structure below. An electron microscope including: an electron source for discharging primary electron beams; electron beam control means for condensing the primary electron beams discharged from the electron source and irradiating a specimen with the primary electron beams; a detector for detecting an electron generated from the specimen; a calculation device for preparing a specimen image on the basis of a signal from the detector; display means for displaying the specimen image; means for recording the displayed specimen image; and specimen holding means for holding the specimen, wherein: the specimen is placed in a capillary through which the primary electron beams are transmittable; the electron microscope includes a supply device for supplying gas or liquid into the capillary and a collection device for collecting the gas or the liquid; and the electron microscope obtains the specimen image of the specimen while flowing the gas or the liquid. 
       Advantageous Effects of Invention 
       [0010]    According to the invention, a change of a specimen can be observed at a high resolution by forming, with a simple structure, a minute gas space, a minute liquid space, or a mixed space of the gas and the liquid, each space containing the specimen in a specimen chamber of an electron microscope, and heating the specimen therein or applying a voltage to the specimen therein. 
     
    
     
       BRIEF DESCRIPTION OF. DRAWINGS 
         [0011]      FIG. 1  is a basic structure diagram of an electron beam apparatus in one example of the invention. 
           [0012]      FIG. 2  is a basic structure diagram of a tip portion of a specimen holder for an electron microscope in one example. 
           [0013]      FIG. 3  illustrates a tip portion of a specimen holder for an electron microscope in one example. 
           [0014]      FIG. 4  is a structure diagram of a specimen pre-evacuation chamber of an electron microscope  1  and specimen holder for an electron microscope in one example. 
           [0015]      FIG. 5  is a top view (a) and a cross-sectional view (b) of a tip portion of a specimen holder for an electron microscope in one example. 
           [0016]      FIG. 6  is a top view of a tip portion of a specimen holder for an electron microscope in one example. 
           [0017]      FIG. 7  is a top view of a tip portion of a specimen holder for an electron microscope in one example. 
           [0018]      FIG. 8  illustrates a tip portion of a specimen holder for an electron microscope in an example. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0019]      FIG. 1  is a basic structure diagram of an electron microscope  1  in one example of the invention. A column of the electron microscope  1  includes an electron gun  2 , condenser lenses  3 , objective lenses  4 , and projection lenses  5 . A specimen holder  6  for an electron microscope is inserted between the objective lenses  4 . A fluorescent screen  7  is provided below the projection lenses  5 , and a TV camera  8  is provided below the fluorescent screen  7 . The TV camera  8  is connected to an image recording unit  9   b  via an image display unit  9   a  and can capture a moving image. The image recording unit  9   b  is connected to a specimen-environment-control unit  10 . 
         [0020]    Apertures  11  for differential pumping are provided between the condenser lenses  3  and the objective lenses  4 . A space between the electron gun  2  and the condenser lenses  3 , a space between the condenser lenses  3  and the objective lenses  4 , an electron microscope specimen chamber  12 , and an observation chamber  13  are connected to different vacuum pumps  15  via respective valves  14 . The specimen holder  6  for an electron microscope includes, in a tip portion thereof, a tubular or square capillary  17  having a thick portion through which electron beams  16  are transmittable, and an inlet  17   a  and an outlet end surface  17   b  of the capillary are communicated to outside of the column of the electron microscope  1 . The inlet end surface  17   a  of the capillary is connected to a gas•liquid supply device  19  via a valve  18 . The gas•liquid supply device  19  includes a flow-rate control unit  19   a  and a store unit  19   b , and is connected to the environment control unit  10 . 
         [0021]    The outlet end surface  17   b  of the capillary is branched, and, in a case where an introduction environment is gas, one branched end surface is connected to an evacuation pump  20  via the opening-closing valve  18 , meanwhile, in a case where the introduction environment is liquid, the one branched end surface is connected to a collection container  21  instead of the evacuation pump  20 . The other branched end surface is connected to the vacuum pump  15  via the valve  14 . 
         [0022]    The electron microscope specimen chamber  12  is connected to a specimen pre-evacuation chamber  22 , and the specimen pre-evacuation chamber  22  is connected to the vacuum pump  15  via the valve  14 . 
         [0023]    A specimen  23  is attached to a tip of a bar-shaped specimen fixing unit  24 , and is placed on a part in the capillary  17 , the part being a part through which electron beams are transmittable. In a case where the specimen  23  is dispersed in a solution; the specimen  23  floated in the capillary  17  or the specimen  23  adhered to a wall surface thereof and the tip of the specimen fixing unit  24  is observed. 
         [0024]    The electron beams  16  generated from the electron gun  2  are condensed by the condenser lenses  3  to thereby irradiate the specimen  23 . The electron beams  16  that have transmitted through the specimen  23  are imaged by the objective lenses  4 , are magnified by the projection lenses  5 , and are projected onto the fluorescent screen  7 . Alternatively, the fluorescent screen  7  is lifted, the electron beams  16  are projected onto the TV camera  8 , and a transmission image is displayed in the image display unit  9   a  and is recorded in the image recording unit  9   b.    
         [0025]    In a case where the specimen holder  6  for an electron microscope is inserted into the electron microscope specimen chamber  12 , inside of the capillary  17  of the specimen holder  6  for an electron microscope is slowly evacuated in advance by the vacuum pump  15  in the specimen pre-evacuation chamber  22  at the same time when the specimen pre-evacuation chamber is evacuated, and is then inserted into the electron microscope specimen chamber  12 . A desired gas-liquid flow rate and a desired pressure in an environment in the vicinity of the specimen are inputted in the specimen-environment-control unit  10  and are set to be desired conditions in the supply device  19 . Gas, liquid, and a mixed fluid thereof are supplied from the supply device  19 , and the gas, the liquid, and the mixed fluid are introduced into the capillary  17 . A transmission image of the specimen  23  in an environment of the gas, the liquid, and the mixed fluid is captured by the TV camera  8 . The transmission image is displayed in the image display unit  9   a  and is continuously recorded in the image recording unit  9   b . In the specimen-environment-control unit  10 , an environment condition in the vicinity of the specimen  23  is constantly monitored and is recorded while being synchronized with a counter of the image recording unit  9   b . The gas introduced into the capillary is evacuated by the vacuum pump  20  connected to the outlet end surface  17   b  of the capillary or is collected by the collection container  21  connected to the outlet end surface  17   b  thereof. Conditions such as a flow rate, a pressure, and a temperature and a humidity in an environment, and a video counter during operation of the apparatus are recorded in the specimen-environment-control unit  10 . 
         [0026]      FIG. 2  is a basic structure diagram of the tip portion of the specimen holder  6  for an electron microscope in one example of the invention. The tubular or square capillary  17  is fixed to have a U-shape in the tip portion of the specimen holder  6  for an electron microscope. An electron beam passage hole  25  is provided in the tip  6  portion of the specimen holder for an electron microscope, and a part of the capillary  17  is located in, the passage hole part  25 . Outside of the part of the capillary  17  set in the passage hole part  25  is coated with carbon having a thickness of 20 nm or less in order to prevent charging up by irradiation electron beams. A shaft part of the specimen holder  6  for an electron microscope is hollow, and the capillary  17  is inserted into the hollow part. A thickness of a wall of the capillary  17  set in the passage hole part  25  is a thickness through which the electron beams  16  are transmittable. The thickness of the capillary only needs to be changed in accordance with a condition of an acceleration voltage of the electron beams  16 . A gasket  26  is attached to the capillary  17  in the shaft part in order to separate a vacuum in the tip portion of the specimen holder  6  for an electron microscope from a vacuum in the shaft part. An internal diameter on an evacuation side of the capillary  17  is larger than that on an introduction side thereof so as to perform evacuation more efficiently. The capillary  17  can be removed together with the gasket  26  from a back end part of the specimen holder  6  for an electron microscope. 
         [0027]      FIG. 3  illustrates the tip portion of the specimen holder  6  for an electron microscope in one example of the invention. The specimen  23  is attached to the tip of the bar-shaped specimen fixing unit  24 . The specimen  23  itself may be directly fixed to the fixing unit  24 . Alternatively, by attaching, to the tip of the fixing unit  24 , a mesh-like support which is stretched with a polymeric membrane or the like and which has a size that can be inserted into the capillary  17 , the specimen  23  may be placed on the mesh-like support. A terminal of the bar-shaped specimen fixing unit  24  is pulled out together with the capillary  17  to outside of the column, and is connected to the rotation mechanism  27 . The specimen can be turned by 360 degrees and can be moved in a horizontal direction in the capillary by the rotation mechanism  27 . The mesh attached to the tip of the specimen fixing unit  24  can be also used to collect the specimen  23  in introduced gas or an introduced solution. The rotation mechanism  27  is connected to the specimen-environment-control unit  10  via a specimen rotation control unit  28 . 
         [0028]      FIG. 4  is structure diagram the specimen pre-evacuation chamber  22  of the electron microscope  1  and the specimen holder  6  for an electron microscope in one example of the invention. A terminal part of the specimen holder  6  is provided outside the column, and the inlet end surface  17   a  and the outlet end surface  17   b  of the capillary incorporated into the holder  6  are also provided outside the column. The inlet end surface  17   a  of the capillary is connected to the gas•liquid supply device  19  via the valve  20 . The gas•liquid supply device  19  includes the flow-rate control unit  19   a  and the store unit  19   b , and is connected to the environment control unit  10 . The specimen rotation mechanism  27  provided in the inlet end surface  17   a  of the capillary is connected to the environment control unit  10  via the specimen rotation control unit  28 , and an angle of the specimen during operation of the apparatus is recorded together with an image in the environment control unit  10 . 
         [0029]    The specimen pre-evacuation chamber  22  is connected to the vacuum pump  15  via the slow leak valve  14 , and a branched one of the capillary outlet end surface  17   b  of the specimen holder  6  is connected to the vacuum pump  15  via the opening-closing valve  18  and the slow leak valve  14 . The other branched one of the capillary outlet end surface  17   b  is connected to the collection container  21  or a mass spectrometer  29  via the valve  18 . The mass spectrometer  29  is connected to the vacuum pump  20  and the specimen-environment-control unit  10 . By introducing gas into the capillary  17  and then analyzing the evacuated gas, it is possible to analyze a reaction product in the capillary  17  and to associate this analysis with an observation result. A result of the analysis is recorded together with a specimen environment condition in the specimen-environment-control unit  10 . 
         [0030]      FIG. 5  is a top view (a) and a cross-sectional view (b) of the tip portion of the specimen holder  6  for an electron microscope in another example of the invention. A diameter of a part of the capillary  17  on a gas and liquid introduction side is reduced, and the part has the electron beam passage hole  25 . This makes it possible to prevent an image from blurring due to large scattering of electron beams because of gas and liquid, and therefore it is possible to make observations at a high resolution. 
         [0031]      FIG. 6  is a top view of the tip portion of the specimen holder  6  for an electron microscope in another example of the invention. A part other than an electron-beam- 16  transmission part of the capillary  17  through which the electron beams  16  are transmittable is covered by a metal membrane or a conductive resin membrane  30 . Therefore, it is possible to prevent decrease in pressure resistance, heat resistance, and mechanical strength. 
         [0032]      FIG. 7  is a top view (a) of the tip portion of the specimen holder  6  for an electron microscope in another example of the invention. A heater  31  is provided in the electron-beam- 16  transmission part of the capillary  17  through which the electron beams  16  are transmittable, and the specimen  23  is directly adhered to the heater part  31 . Both ends of the heater  31  are pulled out to outside of the capillary  17  and are connected to a power supply  32  for heating. The power supply  32  for heating is connected to the specimen-environment-control unit  10 , and a heating condition is recorded in the environment control unit  10 . Therefore, it is possible to observe a change of the specimen  23  at a high temperature in gas. Alternatively, as illustrated  FIG. 7(   b ), the U-shaped capillary  17  is provided only in the tip portion of the specimen holder  6 , and an end portion of the heater  31  set in the capillary  17  is connected to electrodes  33  provided on an outside part of the gasket  26  for separating a vacuum. Therefore, it is easy to adjust a position of the heater  31  and fix the specimen  23  to the heater  31 . 
         [0033]      FIG. 8  illustrates the tip portion of the specimen holder  6  for an electron microscope in another example of the invention. A part of the capillary  17  in the tip portion of the specimen holder  6  for an electron microscope is covered by a hole cup  34  made from metal, and a metal plate  35  extending into the capillary  17  is provided to the hole cup  34 . The specimen  23  is attached to the tip of the specimen fixing unit  24 , and is brought into contact with the metal plate  35 . Another end part of the specimen fixing unit  24  which is taken out to outside of the column of the microscope  1 , and a superimposed voltage power supply unit  36  for superimposing a voltage to a metal plate  35  attached to the metal hole cup part  34  in the capillary  17  are provided. The superimposed voltage power supply unit  36  is connected to the specimen-environment-control unit  10 , and a condition is recorded in the environment control unit  10 . Therefore, it is possible to superimpose a voltage to the specimen  23  in gas and liquid and dynamically observe a change of the specimen  23 . 
       REFERENCE SIGNS LIST 
       [0000]    
       
           1  electron microscope 
           2  electron gun 
           3  condenser lens 
           4  objective lens 
           5  projection lens 
           6  specimen holder for electron microscope 
           7  fluorescent screen 
           8  TV camera 
           9   a  image display unit 
           9   b  image recording unit 
           10  specimen-environment-control unit 
           11  differential pumping aperture 
           12  electron microscope specimen chamber 
           13  observation chamber 
           14  valve 
           15  vacuum pump 
           16  electron beam 
           17  capillary 
           17 A capillary inlet 
           17   b  capillary outlet 
           18  opening-closing valve 
           19  gas•liquid supply device 
           19   a  flow rate control unit 
           19   b  store unit 
           20  evacuation pump 
           21  collection container 
           22  specimen pre-evacuation chamber 
           23  specimen 
           24  specimen fixing unit 
           25  electron beam passage hole 
           26  gasket 
           27  rotation mechanism 
           28  specimen rotation control unit 
           29  mass spectrometer 
           30  metal or conductive resin membrane 
           31  heater 
           32  power supply for heating 
           33  electrode 
           34  hole cup 
           35  metal plate 
           36  superimposed voltage power supply unit