Fig.3 Stealth or C-Dimer. As high as 441K we do not see the C-dimer diffuse. However, at higher temperatures we not only see dimers in this configuration diffuse, but we see conversions between this metastable state and the A-dimer. The reason for the in-shop name is that, compared to the bright streak of a A-dimer, the C-dimer images as only a shadow between rows. See The Ad-Dimer Configurations page of the Gallery for energies and a larger diagram.

Fig. 5. Across the Rows Diffusion involving Intermediate "Stealth"/C-Dimer State. Here a low energy A-type dimer random walks along the top of a row, rotates, and slips between the rows to be a metastable C-type. The dimer then slowly diffuses along the trough, before climbing to an adjacent row where it resumes its diffusion as an A-dimer. Note that through this process the dimer changes rows. This is an excerpt from a longer movie that may either be viewed as a Java Applet or as an Animated GIF. For a discussion of the diffusion mechanisms along the row and along the trough, see The Piecewise Diffusion of the Si Dimer. Image Rate= 1/4.6min; Temperature= 475K.



Dimer Diffusion Across the Rows

Stealth Publication

Fig.4 Filled vs. Empty State Images of a Stealth Dimer. While the filled state image shows only a buckling of the rows, the empty state image allows us to see that there is indeed a dimer between the rows. Note: rows and troughs trade appearances as the bias switches.(Fig.3 was taken with about +2 Volt bias, thus the stronger image of the buckling.)