Near field mapping

Beermann, J., Bozhevolnyi, S., Balzer, F., and Rubahn, H.-G. (2005). Two-photon near-field mapping of molecular orientations in organic nanofibers. Laser Physics Letters, submitted. 

Figure 2.7 (a) Tip-enhanced near-field Raman spectral mapping ofthe adenine nanocrystal at 30 nm intervals, (b) Raman intensity distribution of two major bands at 739 cm and 1328cm. ... 

Near-field optical mapping of exdton wave functions in a GaAs quantum dot. Phys. Rev. Lett., 91, 177401 (4 pages). 

IR and Raman line shapes have been measured for H0D/H20. They peak near 2500 cm 1 and have line widths in the 160 to 180 cm 1 range. Corcelli et al. [151] calculated these line shapes using the approaches described in Section III.C, for the SPC/FQ model, for temperatures of 10 90°C, finding quite good agreement with experiment. More recently, we have extended the method involving the quadratic electric field map for HOD/D20 [98] to HOD/H20 [52] and have calculated IR and unpolarized Raman line shapes. These line shapes, in comparison with experimental line shapes [12, 52], are shown in Fig. 7. Agreement between theory and experiment is excellent for both the IR and Raman. 

The concept of a structure-field map (1) has proven useful in systematizing the occurrence of different structures among a range of fixed-stoichiometry compounds of the A yO type studied here. A binary phase diagram is constructed in which the axes represent the crystal radii (2) of the A and B ions, r and rg, for the appropriate near-neighbor configuration. 

Once illustrated on a map of the industry s effluent plume, the ZPE can be seen visually as larger or smaller than the area of the plume defined by the isopleth for the 1% concentration of effluent (EC, 1999). A ZPE should be estimated for each test species and then illustrated on a site map. As well, it is possible to compare the zones of potential effect for sublethal tests with the locations of exposure areas (generally the near-field) that have been or are to be sampled for fish and benthic invertebrates. This comparison illustrates the relationship between the sublethal tests and potential industry related effects observed in field measurements of fish and benthic invertebrates. 

Unfortunately, the diffraction limit does not permit spectral images to be collected from cells unless the near-field advantage is exploited. However, we have mapped mytotic cells using Raman imaging microspectroscopy, and have reported spectral images of mytotic cells in the telophase and metaphase.17... 

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. 

J. Veerman, M. Garcia-Parajo, L. Kuipers and N. van Hulst, Single molecule mapping of the optical field distribution of probes for near-field microscopy, J. Microsc. 194, 477 (1999). 

Figure 10.11 Near-field imaging of SHG signals from a single Au nanoparticle.250 (a) Schematic of experimental setup (b) AFM image of an elliptical nanoparticle (c, d) near-field SHG signal mapping with emission detection polarized parallel and perpendicular to incident excitation. (Reprinted with permission from M. Zavelani-Rossi et al., Appl. Phys. Lett. 2008,92, 093119. Copyright 2008 American Institute of Physics.) (See color insert.)...

Fourier-Transform Infrared (FTIR) spectroscopy as well as Raman spectroscopy are well established as methods for structural analysis of compounds in solution or when adsorbed to surfaces or in any other state. Analysis of the spectra provides information of qualitative as well as of quantitative nature. Very recent developments, FTIR imaging spectroscopy as well as Raman mapping spectroscopy, provide important information leading to the development of novel materials. If applied under optical near-field conditions, these new technologies combine lateral resolution down to the size of nanoparticles with the high chemical selectivity of a FTIR or Raman spectrum. These techniques now help us obtain information on molecular order and molecular orientation and conformation [1],... 

Simultaneous account for local field and local density of photon states enhancements in close proximity to a silver ellipsoidal nanopaiticle is found to provide up to 10 -fold Raman scattering cross-section rise up. A model of the so-called hot points in surface enhanced spectroscopy has been elaborated as local areas with high Q-factor at incident and scattered (emitted) light frequencies. Further experiments are proposed towards verification of the model in terms of transient Raman experiments to clarify incident field enhancement and scanning near-field optical mapping of local density of photon states. 

Like the STM, the atomic force microscope (AFM) uses a very sharp tip to probe and map sample topography. The AFM detects near-field forces between the tip and sample, instead of detecting the tunneling current. Knowledge of the near-field forces acting between tip and sample is necessary for us to understand the AFM working principles. There are several types of the near-field forces which are briefly described as follows. 

Instrumentation. In both cases, a near field probe is employed—either a metal-coated fiber (aperture-based) or a metal tip (apertureless). Distance regulation, as used with scanning probe methods (see Sect. 7.2), controls the probe-surface gap it may also be used to obtain a topographic mapping of the studied surface. Scattered light is collected and guided to a Raman spectrometer. In a (non-electrochemical) study, dye-labeled DNA that had adsorbed onto evaporated silver layers on FIFE nanospheres was observed [531]. Special surface sites with particularly high enhancement could be identified. 

Fig. 10.18 Spectral mapping of the near-field Raman spectra. The laser power is 0.5 mW at the sample, and the exposure time is 5 s. (Reprinted with permission from Ref. [137].)...

C.R. McNeill, H. Frohne, J.L. Holdsworth, J.E. Furst, B.V. King, and P.C. Dastoor, Direct photocurrent mapping of organic solar cells using a near-field scanning optical microscope. 

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