Nanostructured surface

The last problem of this series concerns femtosecond laser ablation from gold nanoparticles [87]. In this process, solid material transforms into a volatile phase initiated by rapid deposition of energy. This ablation is nonthermal in nature. Material ejection is induced by the enhancement of the electric field close to the curved nanoparticle surface. This ablation is achievable for laser excitation powers far below the onset of general catastrophic material deterioration, such as plasma formation or laser-induced explosive boiling. Anisotropy in the ablation pattern was observed. It coincides with a reduction of the surface barrier from water vaporization and particle melting. This effect limits any high-power manipulation of nanostructured surfaces such as surface-enhanced Raman measurements or plasmonics with femtosecond pulses. 

Inoue H, Brankovic SR, Wang JX, Adzic RR. 2002. Oxygen reduction on bare and Pt monolayer-modified Ru(OOOl), Ru(lOl-O) and Ru nanostructured surfaces. Electrochim Acta 47 3777-3785. 

The creation of nanostructured surfaces is one thing, the study of electrochemical reactions on such nanostructures is another one. Especially in electrocatalysis, where size effects on reactivity are often discussed, there have been attempts to use the tip of an STM as a detector electrode for reaction products from, say, catalytically active metal nanoclusters [84]. Flowever, such ring-disk-type approaches are questionable,... 

In order to achieve stationary and highly spherical microdroplets, the possibility to use superhydrophobic nanostructured surfaces has also been explored to make lasing22 and Raman lasing microdroplets23, where the high contact angle makes it possible to make long-term measurements on nearly spherical microdroplets at rest. 

In order to overcome this drawback, there are two main approaches for the surface modification of carbon nanostructures that reoccur in the literature. The first one is covalent functionalization, mainly by chemical bonding of functional groups and the second one is noncovalent functionalization, mainly by physical interactions with other molecules or particles. Both strategies have been used to provide different physical and chemical properties to the carbon nanostructures. Those that will be presented here are only a few examples of the modifications that can be achieved in carbon nanostructure surfaces and composite fabrication. 

The nanostructured surfaces resemble, at least to a certain degree, the architecture of physiological adhesion substrates, such as extracellular matrix, which is composed from nanoscale proteins, and in the case of bone, also hydroxyapatite and other inorganic nanocrystals [16,17,24-27]. From this point of view, carbon nanoparticles, such as fullerenes, nanotubes and nanodiamonds, may serve as important novel building blocks for creating artificial bioinspired nanostructured surfaces for bone tissue engineering. 

Optical frequency up-conversion, or second harmonic generation (SHG), in nanostructured surfaces can be also considered as a kind of field enhance-menf [61]. In general, SHG efficiency is proportional to the square of nonlinear polarization ha (x [P (2second order susceptibility. For a nanostructured surface, the incident field is transformed to the local field given by Eq. 19, yielding ... 

Up to now, most efforts have been directed towards the preparation of uniformly sized spherical MIP particles in the micrometre range. This is the obvious consequence of the need for this kind of materials as fillers for high-performance chromatographic columns, capillaries for electrophoresis, cartridges for solid-phase extractions and other applications requiring selective stationary phases. Additionally though, strategies for the preparation of other more sophisticated MIP forms, such as membranes, (nano)monoliths, films, micro- and nanostructured surfaces etc. 

It is possible to prepare optically active substrates by immobilising nanoparticles. Nanostructured surfaces have proven to be effective in biosensing [61], but are incompatible with other applications like tissue culture. Because the preparation... 

F. Rosei, Nanostructured surfaces Challenges and frontiers in nanotechnology, J. Phys. Condens. Matter 16, S1373 (2004). 

Supramolecular and constitutional dynamic interfaces and layers have evidently not been consciously much employed to date in biosensing and transport applications. They may provide some initial chemical synthetic difficulties when compared to using naturally derived substances such as phospholipid and cholesterol based components but they may provide a route to nanostructured surfaces and particles demonstrating unknown specificities and behaviours. 

Gay G, Alloschery O, De Lesegno BV, O Dwyer C, Weiner J, Lezec HJ (2006) The optical response of nanostructured surfaces and the composite diffracted evanescent wave model. Nat Phys 2 262-267... 

Keywords Nanostructures Surface plasmon resonance Localized surface plasmon resonance Bio-molecular interactions Refractive index change Effective medium Thin films Biosensors Sensitivity Nanoparticles... 

Nanostructure-based LSPR biosensing has been classified into three schemes surface-relief nanostructures, surface-relief nanostructures coupled to nanoparticles, and nanoparticles. These schemes share many aspects of plasmon characteristics in common, such as shape and concentration dependence. Local field enhancement as a result of plasmon excitation can be used for highly sensitive biosensing. Given particular bio-sensing applications, one of these schemes can be selected to meet... 

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