Near-field scattering

Fig. 7.25. Focusing principles in microscopy left, classical objective middle near field with aperture, right near field scattering tip resolution as indicated, arrow indicates path of light...

Figure 12.8 Calculated near-field scattering amplitude s and phase qp plotted against the ratio of the distance z between the point dipole (which approximates the spherical...

Figure 13.3 (a) Estimated near-field scattering efficiency, of a gold nanosphere In air as a function of particle diameter. is a measurement of the particle s ability to convert incident electric field intensity into a near-field intensity. The efficiency term is... 

Freedom to choose between absorption and near-field scattering dynamics... 

This corresponds to the physician s stethoscope case mentioned above, and has been realized [208] by bringing one leg of a resonatmg 33 kHz quartz tiinmg fork close to the surface of a sample, which is being rastered in the x-y plane. As the fork-leg nears the sample, the fork s resonant frequency and therefore its amplitude is changed by interaction with the surface. Since the behaviour of the system appears to be dependent on the gas pressure, it may be assumed that the coupling is due to hydrodynamic mteractions within the fork-air-sample gap. Since the fork tip-sample distance is approximately 200 pm -1.120), tire teclmique is sensitive to the near-field component of the scattered acoustic signal. 1 pm lateral and 10 mn vertical resolutions have been obtained by the SNAM. 

With regard to the confinement and enhancement ability of a metallic nano-tip, we have proposed near-field Raman microscopy using a metallic nano-tip [9]. The metallic nano-tip is able to enhance not only the illuminating light but also the Raman scattered light [9, 15, 16]. Figure 2.5 illustrates our nano-Raman microscope that mainly comprises an inverted microscope for illumination and collection of Raman... 

Hayazawa, N Inouye, Y Sekkat, Z. and Kawata, S. (2000) Metallized tip amplification of near-field Raman scattering. Opt. Commun., 183, 333-336. 

Verma, P., Yamada, K, Watanabe, H Inouye, Y. and Kawata, S. (2006) Near-field Raman scattering investigation of tip effects on C60 molecules. Phys. Rev B, 73, 045416. 

We also tried measurements to demonstrate that hot spots make significant contributions to surface enhanced Raman scattering [34]. For this purpose, the sample of nanoparticie assembly was doped with Raman active molecules by a spincoating method, and near-field excited Raman scattering from the sample was recorded. We adopted Rhodamine 6G dye as a Raman active material, which is... 

To summarize, we have shown here that enhanced electric-field distribution in metal nanoparticle assemblies can be visualized on the nanoscale by a near-field two-photon excitation imaging method. By combining this method and near-field Raman imaging, we have clearly demonstrated that hot spots in noble metal nanoparticle assemblies make a major contribution to surface enhanced Raman scattering. 

First, the shear layer thickness at various axial locations in the near field was quantified using time-averaged Mie-scattering images. The shear layer thickness was defined as the radial distance over which the average Mie-scattering intensity dropped from 90% to 10% of the core value. Figure 29.7 shows the results... 

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. 

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