Local field enhancement modification

The local field enhancement factor, characterizing the modification of absorption. This results, in most cases of interest, in an enhancement, and possibly a very large enhancement up to = 10. ... 

A larger modification is predicted when the resonance occurs beyond the free-space fluorescence peak (case D of Fig. 2.2(b)). The MEF signal is however much smaller because of the small local field enhancement factor at. ... 

To examine the role of the LDOS modification near a metal nanobody and to look for a rationale for single molecule detection by means of SERS, Raman scattering cross-sections have been calculated for a hypothetical molecule with polarizability 10 placed in a close vicinity near a silver prolate spheroid with the length of 80 nm and diameter of 50 nm and near a silver spherical particle with the same volume. Polarization of incident light has been chosen so as the electric field vector is parallel to the axis connecting a molecule and the center of the silver particle. Maximal enhancement has been found to occur for molecule dipole moment oriented along electric field vector of Incident light. The position of maximal values of Raman cross-section is approximately by the position of maximal absolute value of nanoparticle s polarizability. For selected silver nanoparticles it corresponds to 83.5 nm and 347.8 nm for spheroid, and 354.9 nm for sphere. To account for local incident field enhancement factor the approach described by M. Stockman in [4] has been applied. To account for the local density of states enhancement factor, the approach used for calculation of a radiative decay rate of an excited atom near a metal body [9] was used. We... 

Mono-molecular surface layers exhibit strong effects in small colloidal particles. In the visible region even sub-monomolecular ad-layer of sulfides, iodides, oxides or borates lead to a significant modification of the plasmon resonance [9] (Figure 9). Ordered arrays of metal-columns deposited on, imprinted in or etched out of a substrate surface allow the excitation of extended plasmons similar to colloid arrays. Sharp tip structures allow high local fields and thus enable efficient energy transfer applied e.g. in surface enhanced Raman scattering (SERS). 

The directional properties of the local field electromagnetic enhancement have been used to deduce the orientation of small molecules adsorbed on Ag colloids and electrodes. Moskovits and Suh and Creighton "" used these properties to deduce surface selection rules, which essentially are the modifications of band intensities due to the normal and tangential enhancement components of the local field of a molecule near a metal surface. Here the... 

The Purcell s original idea [10] on modification of photon spontaneous emission rate is extended to modification of photon spontaneous scattering rate. Simultaneous account for local incident field and local density of photon states enhancements in close proximity to a silver nanoparticle is found to provide up to lO -fold Raman scattering cross-section rise up. Thus, single molecule Raman detection is found to be explained by consistent quantum electrodynamic description without chemical mechanisms involved. 

The chemical properties of a protein fimctional group are strongly influenced by its local environment, such as polarity of the microenvironment, hydrogen bonding effect, field/electrostatic effect, as well as steric and matrix effects. These factors contribute to the selectivity and specificity of chemical modifications. Several strategies can be adapted to enhance the selectivity and specificity ... 

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