Specimen tip and tip holder assembly

Abstract

A specimen tip holder assembly for mounting a specimen tip in a transmission electron microscope (TEM) is described. The specimen tip holder assembly comprises a tip holder for supporting a specimen tip. The tip holder is coupled to an elongate support for movement in a direction substantially perpendicular to the axis of the support. An actuator is mounted to the support for causing motion of the tip holder relative to the support.

1 . A specimen tip holder assembly for mounting a specimen tip in a transmission electron microscope (TEM), the specimen tip holder assembly comprising a tip holder for supporting a specimen tip, the tip holder being coupled to an elongate support for movement in a direction substantially perpendicular to the axis of the support, and an actuator mounted to the support for causing motion of the tip holder relative to the support.  
   
   
       2 . A specimen tip holder assembly according to  claim 1  wherein the movement between the tip holder and the elongate support is substantially rectilinear.  
   
   
       3 . A specimen tip holder assembly according to  claim 1  or  claim 2  wherein the movement between the tip holder and the elongate support is substantially parallel to an optic axis of the TEM.  
   
   
       4 . A specimen tip holder assembly according to  claim 1  wherein the elongate support is provided with an elongate aperture or cavity extending in the direction of movement, and the tip holder comprises a protrusion which slidably engages with the elongate aperture or cavity.  
   
   
       5 . A specimen tip holder assembly according to  claim 4  wherein the elongate aperture or cavity extends in a direction substantially parallel to an optic axis of the TEM.  
   
   
       6 . A specimen tip holder assembly according to  claim 1  wherein the actuator is adapted to be operated from a location remote from the tip holder.  
   
   
       7 . A specimen tip holder assembly according to  claim 1  wherein the tip holder is adapted to removably support a specimen tip.  
   
   
       8 . A specimen tip holder assembly according to  claim 1  which further comprises a specimen tip.  
   
   
       9 . A specimen tip holder assembly according to  claim 7  or  claim 8  wherein the tip holder is provided with clamping means to removably support the specimen tip.  
   
   
       10 . A specimen tip holder assembly according to  claim 7  or  claim 8  wherein the tip holder comprises two members, coupled by a pivot pin, and biassing means for urging the two members towards one another, so as to clamp at least a portion of a specimen tip between them.  
   
   
       11 . A specimen tip holder assembly according to  claim 1  wherein the elongate support is a barrel, and the actuator extends within the barrel.  
   
   
       12 . A specimen tip holder assembly according to  claim 1  wherein the actuator comprises a rotatable camshaft extending along the elongate support, arranged to engage a cam follower provided on a slide forming part of or coupled to the tip holder, such that the slide is caused to move in a direction substantially perpendicular to the axis of the support as the camshaft is rotated.  
   
   
       13 . A specimen tip holder assembly according to  claim 12  wherein the support is further provided with sealing means which prevent the passage of gas between the camshaft and the elongate support.  
   
   
       14 . A specimen tip for supporting a specimen in a transmission electron microscope, the tip being provided with a substantially planar surface onto which a specimen is bonded, and a cut-out located underneath the specimen through which electrons may pass.  
   
   
       15 . A specimen tip according to  claim 14 , wherein the specimen comprises a sample.  
   
   
       16 . A specimen tip according to  claim 15  wherein the specimen further comprises a mounting grid to which the sample is bonded, at least the mounting grid being bonded to the planar surface.  
   
   
       17 . A specimen tip holder assembly according to  claim 1  wherein the tip holder supports a specimen tip according to  claim 14 .  
   
   
       18 . A transmission electron microscope having an evacuated cavity into which a specimen tip holder assembly according to  claim 1  or  claim 17  extends.  
   
   
       19 . A transmission electron microscope according to  claim 18  wherein the actuating means are operable from outside of the evacuated cavity.  
   
   
       20 . A method of mounting a specimen to a specimen tip for supporting a specimen in a transmission electron microscope, the method comprising the steps of: 
 a) applying adhesive to at least part of a planar surface on a specimen tip and/or to at least part of a specimen;    b) positioning the specimen on the specimen tip at a location such that the passage of electrons through an at least partially electron-transparent portion of the specimen is not disrupted by the specimen tip; and    c) bonding the positioned specimen to the specimen tip by means of the adhesive.    
   
   
       21 . A method according to  claim 20 , wherein the specimen comprises a sample.  
   
   
       22 . A method according to  claim 21 , wherein the specimen comprises a mounting grid to which the sample is bonded.  
   
   
       23 . A method according to  claim 22 , wherein the method further comprises bonding the sample to the mounting grid prior to step (a).  
   
   
       24 . A method according to any of  claims 20  to  23  further comprising, prior to step (a) or after step (c), removing at least some of the area of the specimen which overhangs the specimen tip.  
   
   
       25 . A method according to  claim 20  wherein the adhesive is a high vacuum compatible adhesive.