Biomedical subjects

Jill A Miwa

Publications and source records attributed to Jill A Miwa.

4 recordsLinked to original sources

PubMed2006

Rational modulation of the periodicity in linear hydrogen-bonded assemblies of trimesic acid on surfaces.

We demonstrate a surprising cooperative adsorption process at the liquid-solid interface, involving self-assembly in which a three-fold hydrogen-bonding unit (trimesic acid, TMA) is forced into a linear pattern by noncovalent interaction with an alcohol. Our work shows that the unexpected linear pattern formed by coadsorption of TMA and alcohols can be modulated in size by choosing alcohols with different chain lengths.

Crystallography↗

PubMed2006

Azobenzene on Cu(110): adsorption site-dependent diffusion.

Azobenzene and its derivatives can undergo reversible trans-cis isomerizations when irradiated with light, making them potential candidates for optically sensitive materials and devices. The adsorption and diffusion of azobenzene on the Cu(110) surface was investigated with a variable-temperature scanning tunneling microscope. The trans-isomer was observed and found to occupy two adsorption geometries-an energetically stable and a metastable state. Diffusion occurred along the closed-packed [1 -1 0] direction of the surface, and the diffusivity for the two adsorption states was found to differ by approximately 1 order of magnitude.

Journal Article↗

PubMed2006

Ordered assembly of alpha-quinquethiophene on a copper oxide nanotemplate.

The organic semiconductor alpha-quinquethiophene (T5) is used as the active layer in organic field-effect transistors. We have investigated the adsorption of T5 on the (110) surface of copper and on the CuO nanotemplate formed by the high-temperature exposure of Cu(110) to molecular oxygen. The results were obtained with high-resolution scanning tunneling microscopy (STM) under ultra-high-vacuum (UHV) conditions. The adsorption of T5 on copper is an important model system because it mimics the active-layer-electrode interface in organic devices. The molecules were observed to adsorb onto both the pristine Cu(110) surface and the CuO nanotemplate, showing a greater affinity for the pristine copper surface. Surprisingly, however, the T5 molecules assembled with a much higher degree of long-range order on the oxygen-passivated portion of the surface.

Adsorption↗

PubMed2005

Selective adsorption of pyridine at isolated reactive sites on Si(100).

Dative bonding of nitrogen-containing heterocycles offers a strategy for the controlled attachment of aromatic molecules to silicon surfaces. However, while scanning tunneling microscopy shows that pyridine on clean Si(100) initially binds via a dative bonding configuration, slow conversion to a more stable bridging state, destroying the aromaticity, is observed. To restrict adsorption to the dative bonded form, we investigated the interaction of pyridine with isolated reactive sites on partially H-terminated Si(100). While dative bonding on isolated clean dimers is observed, single dangling bonds remain unreacted. This selectivity can be accounted for by the ability of the Si-Si dimers to act as electron acceptors that stabilize the dative bonded species. This observation has important implications for the controlled positioning of single molecules on silicon via dative bonding.

Journal Article↗