It has been shown, by imaging gold (200) planes, that it is possible
to achieve better than 0.20-nm structural resolution in cryo-transmission
electron microscopy (cryo-TEM). This has been done using commercially
available cryo equipment and using a 300-kV field emission gun (FEG) TEM.
The images of 15-nm gold particles embedded in amorphous frozen water
clearly show the (111) planes (separated by 0.235 nm) in gold. Fourier
transform demonstrates the presence of (200) planes in the image, proving
a resolution of better than 0.20 nm. The experimental results are
supported by image simulations using the multislice method. These
simulations suggest that it should be possible to achieve the same
resolution even in smaller particles and particles of lighter elements.
The crucial experimental problem to overcome is keeping the thickness of
the amorphous film low and to work at low electron dose conditions.