Comparison of resolutions of different microscopes.
- STM: shaded area.
- HM: high-resolution optical microscope.
- PCM: phase-contrast microscope
- (S)TEM: (scanning) transmission electron microscope
- SEM: scanning electron microscope
- REM: reflection electron microscope
- FIM: field ion microscope.
Binnig and Rohrer, again on their own, submitted a paper to Helvetica
Physica Acta in late December 1982. This was a further study
of Si(111) providing evidence for the so-called 7x7 reconstruction
(reconstruction refers to the way in which surface atoms rearrange
themselves due to the dangling orbitals that do not connect to other
atoms). They reemphasized that the theory was not yet understood.
STM images do not simply reproduce surface-atom corrugation, but
rather the corrugation of electron wave functions near the Fermi
level. Nonetheless, they claimed, surface structure is reflected.
Binnig and Rohrer also addressed the constituency of scientists
with attachment to rival instrumentation. While they pointed to
STM's greatest advantage, images taken directly in real-space (by
contrast LEED, atom diffraction, and ion channelling are all indirect
in that scattered intensity profiles are compared against a test
model; and they all require periodic surfaces), they also conceded
that STM is just a complement to, not a competitor of, other
forms of microscopy. The image on the left reflects Binnig and
Rohrer's conciliatory stance. In our interview, they reemphasized
that they were not playing in a zero-sum game: the expansion of
STM experimentation does not necessarily imply a loss for other
forms of apparatus.
Further small details: they introduced viton connectors at the
end of each spring, and they mentioned the possibility of resonant
tunneling as a further option with the STM (studying s-V instead
of I-V, s being the tunnel distance). Query: why this journal? Did
a local journal offer quick publication or did Binnig & Rohrer desire
to reach a Swiss audience?
Source: G. Binnig and H. Rohrer, "Scanning
tunneling microscopy", Helvetica Physica Acta, 55 (1982),
726-735, at 734. Reproduced by permission of Birkhäuser Verlag