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Biomedical subjects

B Poelsema

Publications and source records attributed to B Poelsema.

15 recordsLinked to original sources
PubMed2001

Kinetic physical etching for versatile novel design of well ordered self-affine nanogrooves.

Ion bombardment at extreme grazing incidence leads to the formation of remarkably well ordered, one to two atomic layer deep, parallel grooves on a Cu(001) surface. These self-organized grooves are oriented parallel to the ion's plane of incidence and their period can be controlled between approximately 4 and 15 nm. We have identified two distinct temperature regimes: Between about 200 and 300 K the substrate temperature controls the period, while below 200 to about 150 K the ion energy does. The groove separation distribution shows distinct self-affine character. The physical origin of the novel nanostructures is discussed.

Journal Article↗
PubMed2000

Diffusion driven concerted motion of surface atoms: Ge on Ge(001)

The diffusion of Ge dimers on the Ge(001) surface has been studied with scanning tunneling microscopy. We have identified three different diffusion pathways for the dimers: diffusion of on-top dimers over the substrate rows, diffusion across the substrate rows, and diffusion of dimers in the trough. We report on a heretofore unknown phenomenon, namely, diffusion driven concerted motion of substrate atoms. This concerted motion is a direct consequence of the rearrangement of substrate atoms in the proximity of the trough dimer adsorption site.

Journal Article↗