Nano apertures

Wenger J, Lenne PF, Popov E, Rigneault H, Dintinger J, Ebbesen TW (2005) Single molecule fluorescence in rectangular nano-apertures. Opt Express 13 7035-7044... 

Abstract Nanophotonic stractures exhibit a large variety of effects on the nanoscale that can be used for biosensing in a biochip format. The resonance nature of these structures then allows high sensitivity to analytes, gases, or other external index perturbations down to the order of 10 refractive index unit. In this chapter, several configurations of nanophotonic structures and their use for sensing are reviewed with special emphasis on grating-based resonant strucmres, metallic nanoparticle, and nano apertures. 

Fig. 11.5. Nano-electrospray (a) SEM micrograph of the open end of a glass nanoESI capillary having a 2-pm aperture, (b) microscopic view of the spray from a nanoESI capillary as provided by observations optics. By courtesy of New Objective, Woburn, MA.

The molecular size pore system of zeolites in which the catalytic reactions occur. Therefore, zeolite catalysts can be considered as a succession of nano or molecular reactors (their channels, cages or channel intersections). The consequence is that the rate, selectivity and stability of all zeolite catalysed reactions are affected by the shape and size of their nanoreactors and of their apertures. This effect has two main origins spatial constraints on the diffusion of reactant/ product molecules or on the formation of intermediates or transition states (shape selective catalysis14,51), reactant confinement with a positive effect on the rate of the reactions, especially of the bimolecular ones.16 x ... 

It has been concluded that, in most cases, catalytic reactions over zeolites occur within their intracrystalline cages and channels. Zeolite catalysts can therefore be considered as a succession of nano or molecular reactors. The consequence is that the activity, selectivity, but also the stability of all the reactions carried out over zeolite catalysts, depend (slightly or significantly) on the shape and size of cages, channels and of their apertures, hence that shape selectivity is a general characteristic of zeolite catalyzed reactions. 

Similar contributions are present for dipole emission. Emission to the far field is enhanced the most when the dipole is located near the measurement plane, and especially, near the aperture rims where LSP resonances occur. As the dipole moves away from the substrate, the emission decays exponentially. The excitation and emission enhancement characteristics of nano ertures will next be discussed in more detail. 

Figure 17.13 Calculated radiative emission enhancement at two different wavelengths for a dipole placed with nano ertures of diameters ranging from 75nm to 200nm in both aluminum (left) and gold (right) films of ISOnm thickness. The intensity enhancement is averaged for dipoles located within lOnm thick volumes within the apertures, with VI representing the volume adjacent to the substrate. Emitted power is measured through a plane on the substrate side. The upper region is air.

Yuan H. X., Xu B. X., Wang H. F., ChcmgT. C. (2006). Field enhancement of nano-sized metal aperture with and without surrounding corrugations through resonant surface plasmons. Jpn. J. Appl. Phys. 45 787-791. 

In order to understand how nano technology can be used in computer generated holography, we need understand the basics of diffraction theory. This is covered in much better detail in several fundamental texts [12, 13], so we will only summarise the key aspects in this chapter. Let us assume we have an arbitrary aperture (hole) function, A x, y) in the plane S as shown in Fig. 1.1, with coordinates [x, y]. The light passing through this aperture will be diffracted at its edges and the exact form of this pattern can be calculated. We want to calculate the field distribution at an arbitrary position away at the point P, which is a distance R from the aperture. 

Most recently (Schneider 2006) an experimental source was used to conduct studies under conditions of total solvent consumption , with pneumatically assisted nebu-lization to stabilize the ESI process, a heated laminar flow chamber to enhance desolvation and ion production, and various atmosphere-to-vacuum aperture diameters to maximize ion transfer. The motivation for these experiments was to investigate the proposal that the reason for the much lower ionization sampling efficiencies at higher flow rates ( o,L.min and above) is that the electrosprayed droplets are much larger in view of the much larger ESI needle tip diameters required to maintain flow rates in this regime, and thus are much less efficiently evaporated down to the Rayleigh and/or ion evaporation limits than the droplets formed from the 1 (tm diameter tips nsed in nano-ESI (Juraschek 1999 Schmidt 2003). 

The substrate was composed of a dried film of bovine serum albumin (BSA) deposited on glass. The etching enzyme was trypsin, a proteolytic enzyme that cleaves on the carboxyl side of lysine and arginine residues. The enzyme was loaded in solution into a nano-fountain pen (NFP) probe (a capillary, heat-drawn into a sharp tip with an aperture of 100 nm) [2] mounted as the probe of an AFM, and delivered in... 

Lehier C, Frey L, Petersen S, Sulzbach T, Ohlsson O, Dziomba T, Danzebrink HU, Ryssel H. Fabrication of silicon aperture probes for scanning near-field optical microscopy by focused ion beam nano machining. Microelectron Eng 2001 57-8 721-728. 

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