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Fig. 5. Place the freshly cleaved mica sheet
(A)
within a clean ricochet cylinder
(B)
and below a mask
(C)
which shields the mica from direct carbon evaporation. Carbon
rods (
D
and
E
), held in contact by a spring during the evaporation, are positioned
1.5 cm above the mask.
3.3. Preparation of Carbon-Coated EM Grids
1.
Prepare thin carbon films by thermally evaporating a 1-mm long, 0.8-mm diam-
eter spindle from a carbon rod using the geometry shown in
Fig. 5
(
see
Note 5
).
Using a clean ricochet cylinder
(6)
, evaporate the carbon onto a freshly cleaved
sheet of mica (
Fig. 5
) (
see
Note 6
). The film thickness should lie within the range
2.0-3.0 nm
(7)
. Film thickness may be determined using a film thickness moni-
tor, assuming a carbon density of 1.9 g/cm
3
(
see
Note 7
).
2.
Incubate the carbon-coated mica in a humid atmosphere overnight to facilitate
separation of the film.
3.
Using watchmakers forceps, carefully space the EM grids 1-2 mm apart on the
carbon film.
4.
Using the forceps, slowly slide the mica at angle of 10-20
into a reservoir of
ultrapure water. The carbon film should detach from the mica and remain intact
on the surface of the water.
°
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