Near-field effect

Liu, C., Huang, Z., Lu, E. Zheng, W., Hutmacher, D. W., and Sheppard, C. 2006. Near-field effects on coherent anti-Stokes Raman scattering microscopy imaging. Opt. Express 15 4118-31. 

Abstract Optical techniques for three-dimensional micro- and nanostructuring of transparent and photo-sensitive materials are reviewed with emphasis on methods of manipulation of the optical field, such as beam focusing, the use of ultrashort pulses, and plasmonic and near-field effects. The linear and nonlinear optical response of materials to classical optical fields as well as exploitation of the advantages of quantum lithography are discussed. 

The development of surface analytical techniques such as LA-ICP-MS, GDMS and SIMS focuses on improvements to sensitivity and detection limits in order to obtain precise and accurate analytical data. With respect to surface analytical investigations, an improvement of spatial and depth resolution is required, e.g., by the establishment of a near field effect or the apphcation of fs lasers in LA-ICP-MS. There is a need for the improvement of analytical techniques in the (j,m and nm range, in depth profiling analysis and especially in imaging mass spectrometry techniques to perform surface analyses faster and provide more accurate data on different materials to produce quantitative 3D elemental, isotopic and molecular distribution patterns of increased areas of interest with high spatial and depth resolution over an acceptable analysis time. 

Several new developments that enhance efforts to minimize drift are described. Models that predict near field effects of aircraft and mesoscale winds are available. The need for additional efforts to describe flow within canopy and description of conditions for inertial deposition on target elements is outlined. 

Figure 16c is a sample flow map of the liquid velocity profile 221. The gas phase occupies more than 50% of the cross-sectional area of the pipe, and it is not symmetrically distributed above the liquid phase. Figure 16c also shows a higher liquid velocity near the center of the pipe that decreases radially. The lighter (yellow) lines in the lower part of the pipe and near the wall correspond to the liquid velocity values obtained from the power law equation the darker lines (dark gray) above the power law equation values correspond to the near field effect of the transducer. 

The Novotny group has produced similar theoretical results with calculations on spherical nanoparticles, showing that fluorescence enhancement due to metal near field effects is strongly frequency dependent and that florescence enhancement is maximized when the fluorophore emits red-shifted to the plasmon resonance peak of the nanoparticle. They also explained this result as a consequence of the slight offset of the frequency dependence of the quenching term and enhancement term. ... 

Shimada R, Kano H, Hamaguchi H (2008) Intensity enhancement and selective detection of proximate solvent molecules by molecular near-field effect in resonance hyper-Raman scattering. J Chem Phys 129 024505... 

Usually one distinguishes between "near field" and "far field" effects of radioactivity releases. Near field effects are observed close to the release source, as for example the nuclear power plant or nuclear waste storage facility. The dissolution of nuclear waste by rain or ground water is a typical near field problem. As the source is known, it can be controlled and its environment monitored. If the radioactivity exceeds permitted levels, access to the contaminated area can be restricted. Far field effects involve the behavior of radionuclides which have spread out of such a restricted area, caused either by nuclear power accidents and weapons tests or by leakage from nuclear power plants. 

Thus, the ealeulation of the matrix (4) reduees to the ealeulation of the matrices S S, and S°. It is very diffieult to calculate all these matriees for closely paeked media comprising scatterers comparable to the wavelength. In this case, the matrix S° can contribute significantly to the matrix (4), and all the matriees must be calculated with the eoefficients of the addition theorem in the form (7). These coefficients describe all pecuharities of the waves in the vicinity of the scatterers including the near-field effects. For low-density media, when the distances between the particles r. aj, (where the... 

The reflection matrix for a closely packed medium composed of wavelengthsized scatterers can be represented as a sum of matrices (10) with the coefficients of the addition theorem (7). These coefficients describe all the details of the field in the vicinity of any scatterer, including the near-field effects [26]. We consider the manifestations of these effects quahtatively using the field configuration near a spherical scatterer as the simplest example. 

Tip-enhanced Raman spectroscopy (TERS) has been developed from the field of scanning near-field microscopy (SNOM), a field that is not directly related to SERS. Howevei one particular important concept of SNOM is also essential for the SERS process the near-field effect. It is common to both SNOM and the electromagnetic enhancement process of SERS and it is the heart of TERS. 

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