An atomic force microscope reveals that the sliding of a nanotip on a graphite surface occurs through a nanoscale stick-slip mechanism. The angle between the sliding direction and a stiff crystallographic axis determines the periodicity of the slip events defining domains of various friction properties. The experimental data are interpreted using the reaction rate theory, with the energy barrie...

Optical nanotip arrays fabricated on etched fiber bundles were functionalized with DNA spots. Such unconventional substrates (3D and non-planar) are difficult to pattern with standard microfabrication techniques but, using an electrochemical cantilever, up to 400 spots were electrodeposited on the nanostructured optical surface in 5 min. This approach allows each spot to be addressed individual...

decade, [ 15 ] beginning with the use of fi bers as mounting structures [ 16–19 ] and progressing onto the use of scanning probe microscopy (SPM) tips. [ 6,8,13,20,21 ] While mounting nanoparticles onto SPM tips is more diffi cult than with fi bers the additional capabilities of the SPM tip have made such tips desirable. However , these tips typically require complicated assembly processes to p...

The "perfect" vortex is a new class of optical vortex beam having ring radius independent of its topological charge (order). One of the simplest techniques to generate such beams is the Fourier transformation of the Bessel-Gauss beams. The variation in ring radius of such vortices require Fourier lenses of different focal lengths and or complicated imaging setup. Here we report a novel experime...

The method of fluorescence resonance energy transfer scanning near-field optical microscopy (FRET SNOM) consists in the separation of a FRET pair between an SNOM tip and a sample. The donor (or acceptor) centre is located at the tip apex and scanned in the vicinity of a sample while acceptor fluorescence (or donor-fluorescence quenching) is detected. It is shown that the spatial resolution for ...

The purpose of this work is to present elements of a design tool for field emission displays using carbon nanotubes as emitters. We use a continuum model to describe the carbon nanotubes and we use a locally one-dimensional approximation to calculate the emission current. We investigate the emission current to voltage characteristic, screening effects and the lateral spread of the emission curr...

Indentation testing of a brittle material using a notionally `sharp' indenter may reveal several important physical properties, including fracture toughness, surface ®nish information and the residual stress state. In the case of shallow cone indenters, the contact and fracture mechanics is well de®ned and closed-form solutions exist in elasticity theory. However, no real indenter is atomically...

Let Ω be a disk of radius R in the plane. A set F of closed unit disks contained in Ω forms a maximal packing if the unit disks are pairwise disjoint and the set is maximal: i.e., it is not possible to add another disk to F while maintaining the packing property. A point p is hidden within the “forest” defined by F if any ray with apex p intersects some disk of F : that is, a person standing at...