5 OPERATION
EM210F-1
5-45
5.5.3 High Dispersion Electron Diffraction
The maximum lattice spacing that can be analyzed by the selected area diffraction
method is on the order of 10 nanometers. This can be extended, however, to 1,000
nanometers by means of the high dispersion electron diffraction method. However, since
the specimen in this method is easily charged with electrons, coat the specimen on both
sides with carbon if specimen conductivity is very low.
1.
Obtain a conventional image on the screen.
2.
Depress the MAG1 (R1-
③
), and select the desired magnification in the TEM
mode.
3.
Select a magnification to be used using the MAG-CAM L knob (R1-
⑤
).
4.
Select a field of view to be studied.
5.
Carry out the photographing.
6.
Depress the LOW MAG switch (R1-
②
) to obtain the LOW MAG mode. 4.2.5).
7.
Set the magnification to about 500 times.
8.
Focus the image using the OBJ FOCUS knob (R1-
⑥
).
9.
Manipulate the BRIGHTNESS knob (L1-
⑥
) to diverge the beam to the extent
where the entire specimen image appears.
10.
Bring the field of view to be studied to the screen center.
11.
Insert a small condenser aperture (10 or 20
m
m in dia.).
12.
Insert the objective aperture of 5
m
m into the beam path and center it.
13.
Carry out photographing if necessary.
14.
Depress the SA DIFF switch (R1-
②
).
15.
Select a camera length (longer than 400 cm) using the MAG/CAM L knob.
?
The camera lengths that can be varied are 8 to 200 cm, 400 cm and longer and
3303 cm. The 8 to 200 cm camera lengths are for selected area electron diffrac-
tion, the 400 cm and longer camera lengths are for high dispersion electron dif-
fraction, and the 33.3 cm camera length is for high resolution electron diffrac-
tion.
16.
Make sure that a direct spot is on the screen. If the spot cannot be found,
fined it as follows.
a.
Turn the BRIGHTNESS knob (L1-
⑥
) clockwise.
b.
Center the spot using the SHIFT knobs (L1-
⑧
,R1-
③
).
c.
Depress the SA DIFF knob (R1-
②
) again.
d.
Manipulate the DIFF FOCUS knob (R1-
⑦
) to clarify the spot.
17.
Carry out the photographing in the manual exposure mode.
