The method of replication affects metal film granularity and resolution

Author(s):  
George C. Ruben

Single molecule resolution in electron beam sensitive, uncoated, noncrystalline materials has been impossible except in thin Pt-C replicas ≤ 150Å) which are resistant to the electron beam destruction. Previously the granularity of metal film replicas limited their resolution to ≥ 20Å. This paper demonstrates that Pt-C film granularity and resolution are a function of the method of replication and other controllable factors. Low angle 20° rotary , 45° unidirectional and vertical 9.7±1 Å Pt-C films deposited on mica under the same conditions were compared in Fig. 1. Vertical replication had a 5A granularity (Fig. 1c), the highest resolution (table), and coated the whole surface. 45° replication had a 9Å granulartiy (Fig. 1b), a slightly poorer resolution (table) and did not coat the whole surface. 20° rotary replication was unsuitable for high resolution imaging with 20-25Å granularity (Fig. 1a) and resolution 2-3 times poorer (table). Resolution is defined here as the greatest distance for which the metal coat on two opposing faces just grow together, that is, two times the apparent film thickness on a single vertical surface.

2007 ◽  
Vol 1026 ◽  
Author(s):  
Osamu Kamimura ◽  
Kota Kawahara ◽  
Takahisa Doi ◽  
Takashi Dobashi ◽  
Takashi Abe ◽  
...  

AbstractDiffraction microscopy (or diffractive imaging) with iterative phase retrieval was performed using a low-energy (20-keV) electron beam to verify the possibility of high-resolution imaging with low specimen damage. Diffraction patterns of fine and uniform multi-wall carbon nanotubes (MWCNT) were recorded without a post-specimen lens. One- and two-dimensional phase retrievals were processed from the diffraction pattern alone. The reconstructed object images reflected the characteristic structure of the MWCNT. These results show the possibility of high-resolution imaging with a low-energy electron beam.


Author(s):  
J.M. Cowley

By extrapolation of past experience, it would seem that the future of ultra-high resolution electron microscopy rests with the advances of electron optical engineering that are improving the instrumental stability of high voltage microscopes to achieve the theoretical resolutions of 1Å or better at 1MeV or higher energies. While these high voltage instruments will undoubtedly produce valuable results on chosen specimens, their general applicability has been questioned on the basis of the excessive radiation damage effects which may significantly modify the detailed structures of crystal defects within even the most radiation resistant materials in a period of a few seconds. Other considerations such as those of cost and convenience of use add to the inducement to consider seriously the possibilities for alternative approaches to the achievement of comparable resolutions.


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