Scanning Tunneling Microscopy (
STM) uses a thin metal (
tungsten) probe that scans a specimen and produces an image revealing the
bumps and
depressions of the atoms of the surface of the specimen.
The resolving power of an STM is much greater than that of an electron microscope; it can resolve features that are only about 1/100 the size of an atom. Moreover, special prepirations of the specimen for observation is not needed. STMs are used to provide incredibly detailed views of molecules such as DNA.
On a personal note, those are very pricey so I was never lucky enough to use one, thus I cannot give any further details on the subject.