Near-field light

We discuss simple but general 2D configuration of near-field light propagation, that is common in SVD-related studies, see Fig. 1. It is assumed that all the light sources are located within interval [-Xq, Xo] at the source plane S, and the light field distribution is analyzed within interval [->>o, To] at observation plane P. This... 

Near-field light collection in shear-force mode requires reflection back to an illuminated tip that is in shear-force contact " with the surface in question. Therefore,... 

Scattering near-field optical microscopy (SNOM) Focuses a laser beam to a sharp tip that is close to a surface and collects the scattered near-field light with separation from the far-field light by modulation techniques. 

The sample films for SNOM measurements were prepared by the LB technique. Figure 15 shows the layer structure. The PiBMA layer in the middle, in which a very small quantity of PiBMA-Pe was embedded, was sandwiched between the non-labeled layers of poly(vinyl octanal acetal). The near field light from the probe tip excites the Pe dyes attached to the labeled PiBMA-Pe chains that constitute a part of the monolayer film. Thus, the very thin and transparent LB film with a flat surface is regarded as an ideal SNOM sample without any artifacts caused by tip-sample interaction. 

Dunn R C, Holtom G R, Mets L and Xie X S 1994 Near-field fluorescence imaging and fluorescence lifetime measurement of light harvesting complexes in intact photosynthetic membranes J. Chem. Phys. 98 3094-8... 

Nc.ar-Fi ld Scanning Optical Microscope.. The near-field scanning optical microscope (NSOM) should, strictiy speaking, be NSLM for near-field scanning light microscopy because "optical" includes electron optical as well as light optical and NSOM is a light microscope. 

The primary photochemical act, subsequent to near-uv light (wavelengths <400 nm) absorption by Ti02 particles, is generation of electron—hole pairs where the separation (eq. 3) into conduction band electrons (e g ) and valence band holes (/lyB ) faciUtated by the electric field gradient in the space charge region. Chemically, the hole associated with valence band levels is constrained at... 

A nano-light-source generated on the metallic nano-tip induces a variety of optical phenomena in a nano-volume. Hence, nano-analysis, nano-identification and nanoimaging are achieved by combining the near-field technique with many kinds of spectroscopy. The use of a metallic nano-tip applied to nanoscale spectroscopy, for example, Raman spectroscopy [9], two-photon fluorescence spectroscopy [13] and infrared absorption spectroscopy [14], was reported in 1999. We have incorporated Raman spectroscopy with tip-enhanced near-field microscopy for the direct observation of molecules. In this section, we will give a brief introduction to Raman spectroscopy and demonstrate our experimental nano-Raman spectroscopy and imaging results. Furthermore, we will describe the improvement of spatial resolution... 

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... 

Figure 2.5 A tip-enhanced near-field Raman microscope which we have developed. The microscope is based on AFM for control of the metallic nano-tip, an inverted optical microscope for illumination/collection of the light field and a polychromator for measurement of the Raman signal.

Nonlinear optical phenomena, as well as near-field optics, provide us with super resolving capability [20]. The probability of nonlinear optical phenomena is proportional to the number of photons which participate in the phenomenon. For example, the intensity distribution of two-photon excited fluorescence corresponds to the square of the excitation light. Thus, we proposed a combination of the field... 

Kottmann, J. P., Martin, O. J. F Smith, D. R. and Schultz, S. (2001) Non-regularly shaped plasmon resonant nanopartide as localized light source for near-field microscopy. J. Microsc., 202, 60-65. 

For near-field imaging based on nonlinear or ultrafast spectroscopy, light pulses from a femtosecond Ti sapphire laser (pulse width ca. 100 fs, repetition rate ca. 

We usually use white light from a Xe discharge arc lamp for the measurement of near-field transmission images and spectra [9]. The spectrum of transmitted light... 

In summary, it has been demonstrated that plasmon-mode wavefunctions of gold nanoparticles resonant with the incident light can be visualized by near-field transmission imaging. 

Nagahara, T., Imura, K. and Okamoto, H. (2004) Time-resolved scanning near-field optical microscopy with supercontinuum light pulses generated in microstructure fiber. Rev. Sci. Instrum., 75, 4528-4533. 

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