The thickness of the film is determined by the number of monolayers plus surface pyrrole. However, they are all excellent conductors and extremely resistant to electron beam damage. 2 shows a plot of the measured film thickness versus the time of exposure to pyrrole vapor. Since these films are of low Z material, they are good for visualizing biological molecules and most samples seem to adhere very well to them. When the thickness is just right, they are extremely uniform with little graininess.
Further work is needed to eliminate lumpiness without sacrificing mechanical strength.
Other possibilities are to chemically tailor the surface to the specific biological application, e.g. to use bilayers for membrane proteins. STEM image of TMV which was unstained but air-dried. The full width of the micrograph is 0.512 microns, the diameter of TMV is 18 nm, and the thickness of the film is 3.9 nm. The thickness of the film plotted in A versus the length of time the C 16 -pyrrole film, cast on 0.02M FeCl 3 for 5 min, was exposed to pyrrole vapor. References J. S. Wall , J. F. Hainfeld and K. D. Chung.