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The dependence of the optical properties of spherical gold nanoparticles on particle size and wavelength were analyzed theoretically using multipole scattering theory, where the complex refractive index of gold was corrected for the effect of a reduced mean free path of the conduction electrons in small particles. To compare these theoretical results to(More)
The measurement of the electrical properties of molecules, down to the single molecule level, has become an experimental reality in recent years. A number of methods are now available for experimentally achieving this feat. The common aim of these methods is to entrap a single or small numbers of molecules between a pair of metallic contacts. This topical(More)
A series of thioacetate-terminated butadiyne-linked porphyrin oligomers have been synthesized with one to three porphyrin repeat units. Single molecule electrical scanning tunneling microscopy measurements using the I(s) and I(t) methods were used to determine the molecule conductances for this series of oligomers. The molecular conductance shows an(More)
Spontaneous formation of stable molecular wires between a gold scanning tunneling microscopy (STM) tip and substrate is observed when the sample has a low coverage of alpha,omega-dithiol molecules and the tunneling resistance is made sufficiently small. Current-distance curves taken under these conditions exhibit characteristic current plateaux at large(More)
It is now becoming clear that the characteristics of the whole junction are important in determining the conductance of single molecules bound between two metal contacts. This paper shows through measurements on a series of seven conjugated molecular bridges that contact separation is an important factor in determining the electrical response of the(More)
There is much discussion of molecules as components for future electronic devices. However, the contacts, the local environment and the temperature can all affect their electrical properties. This sensitivity, particularly at the single-molecule level, may limit the use of molecules as active electrical components, and therefore it is important to design(More)
We present a new route to single-molecule sensing via solvation shells surrounding a current-carrying backbone molecule. As an example, we show that the presence of a water solvation shell "gates" the conductance of a family of oligothiophene-containing molecular wires, and that the longer the oligothiophene, the larger is the effect. For the longest(More)
A systematic experimental study of the electrical conductance of single alkanedithiol molecules (HS-(CH(2))(N)-SH) between gold contacts in air for N = 3-12 is presented. For all of these molecules, three different fundamental conductance groups (low, medium and high conductance) were observed. For long molecules (N > 7) the conductance decays exponentially(More)
We report here on the fabrication of a three-dimensional array of nanoparticles which bridges the gap between lithographically defined gold electrode contacts separated by 20 nm. The nanoparticle assemblies are formed from about 5 nm gold nanoparticles and benzenedimethanethiol (BDMT) bridging ligands. These assemblies are introduced between the contacts(More)