Local nano environment

Previous lifetime measurements on higher concentrated samples [6, 13, 14] resulted in time constants of 21.7-24.5 ns and agree very well with the presented results on individual molecules. Although only four different molecules were investigated, all time constants fall within the experimental accuracy interval and the statistical variation is very low. The average of the four time constants is 24 ns (single exponential fit) with a standard variation of 0.5 ns or 2%. As expected, the lifetime of the excited molecule is not very sensitive to its local nano-environment. 

The molecular symmetry is broken by the interaction with the matrix. The slope of the spectral shift versus the electric field mainly depends on A/7, the change of the local dipole moment, which itself depends on the respective orientations of the applied field, the orientation of the molecule, and its local nano-environment. More precisely, the component of A/ along the local electric field relates to the slope dv/d by the equation ... 

As described above, SERS takes place in the local optical fields of metal nanostructures and is therefore restricted to the inunediate vicinity of the gold nanoparticles (see also Figure 3 for a schematic). Thereby, SERS probes enable the acquisition of Raman signals not only at high sensitivity but also from nanometer scaled volumes. This local confinement of the SERS effect has several advantages over regular Raman experiments For SERS studies in cells, SERS nanoprobes can be positioned at discrete locations, e.g., in a specific cellular compartment, and the spectral information is obtained only from the nano-environment of these probes and hence that particular compartment. This is different from the spectral information collected in a normal Raman microspectroscopic experiment, where all positions in a whole cell are probed. This also means that the maximum lateral resolution in such a Raman experiment... 

Selzer Y, Cai L, Cabassi MA, Yao Y, Tour JM, Mayer TS, Allara DL (2005) The effect of local environment on molecular conduction isolated molecule versus self-assembled mono-layer. Nano Lett 5 61-65... 

A key aspect of metal oxides is that they possess multiple functional properties acid-base, electron transfer and transport, chemisorption by a and 7i-bonding of hydrocarbons, O-insertion and H-abstraction, etc. This multi-functionality allows them to catalyze complex selective multistep transformations of hydrocarbons, as well as other catalytic reactions (NO,c conversion, for example). The control of the catalyst multi-functionality requires the ability to control not only the nanostructure, e.g. the nano-scale environment around the active site, " but also the nano-architecture, e.g. the 3D spatial organization of nano-entities. The active site is not the only relevant aspect for catalysis. The local area around the active site orients or assists the coordination of the reactants, and may induce sterical constrains on the transition state, and influences short-range transport (nano-scale level). Therefore, it plays a critical role in determining the reactivity and selectivity in multiple pathways of transformation. In addition, there are indications pointing out that the dynamics of adsorbed species, e.g. their mobility during the catalytic processes which is also an important factor determining the catalytic performances in complex surface reaction, " is influenced by the nanoarchitecture. 

Ultimately, the water pool and the interfacial surfactant layer can exhibit multiple catalytic effects, which result from the concentrations of reactants localized in the nano-compartmentalized region and the physicochemical properties of the micellar environment. Accordingly, the reversed micellar systems have the possibility of controlling the multiple effects on the reactions by changing the physical factors of the reversed micellar systems such as water mobility, micropolarity, and electrostatic force. 

Dissolved gases or bubbles near a solid also influence the slip flow behaviour. It has been observed experimentally that the amount of slip depends on the type and quantity of dissolved gas in the fluid. From sedimentation studies it has been reported that slip is not observed in vacuum conditions while there is a clear slip when a liquid sample is in contact with air. Slip in non-wetting systems depends strongly on the environment in which the experiment is performed. Dissolved gases or nano-huhhles in the nearwall region are thought to create localized defects increasing the possibility of slip. 

The mechanism of trans-cis photoisomerization in azobenzenes proceed either via rotation about the azo bond with the mpture of the tt-character under n-n excitation, or via inversion mechanism under n-jT excitation, where the iT-bond remains intact. Both mechanisms are shown in Figure 9.3. On the other hand, thermally induced reversible cis-trans back reaction proceeds through a rotational mechanism. The trans-cis photoconversion is almost completely reversible in picoseconds without any side reactions, whereas thermal cis trans conversion usually has timescales ranging from nano- to miUiseconds, or even hours, depending upon the substituent and the local environment A variety of azobenzene systems have been designed and synthesized, including cyclodextrins [40-42], admantanes [43], polycyclics [44], bacteriorodophsin [45], and crown ethers [46]. 

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