Near-field transmission images

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. 

Fig. 4.6 (a) Near-field transmission spectmm of a spherical gold nanoparticle (diameter 100 nm). (b,c) Near-field transmission images taken at 580 and 720 nm, respectively. Scale bar 100 nm... 

Fig. 4.7 (a) Topography of a short gold nanorod (diameter 30 nm, length 180nm). (b) Near-field transmission spectrum taken at the cross point in (a). (c,d) Near-field transmission images taken at 532 and 780 nm, respectively. Scale bars 100nm... 

Wavefunction Images of Plasmon Modes of Cold Nanorod — Near-Field Transmission Method... 

Figure 3.3 Near-field transmission spectra and images of a single gold nanorod (length 510nm, diameter 20nm). The two transmission spectra were obtained at positions 1 and 2 indicated in the inset. Each image was obtained at the resonance peak wavelength. (Reproduced with permission from Royal Society of Chemist [10]).

The resonance energy and the wave vector of the plasmon can be obtained from the extinction peak wavelength of the transmission spectrum and the spatial oscillation period of the image of the nanorod, respectively. By plotting the wave vector of the plasmon vs. the resonance photon energy, the dispersion relation of the plasmon in the nanorod can be determined. Figure 4.10 shows the dispersion relation determined from near-field transmission measurements of various nanorods with... 

Figure 3.5 Near-field static ((a), (b)) and transient ((c)-(e)) transmission images of a single gold nanorod (length 300 nm, diameter 30nm). Observed wavelengths are 750nm (a), 900nm (b), and 780nm ((c)-(e)). The pump-probe delay times in ((c)-(e)) are 0.60,...

Figure 3.6 Near-field transient transmission image of a single gold nanorod observed at 0.6 ps (a) and corresponding simulated image (b). (Reproduced with permission from The American Physical Society [27]).

For nearly two hundred year s microscopy as a science depended on the use of visible and, rarely, near UV electromagnetic radiation. In the early part of this century developments in theoretical Physics opened other avenues of seeing objects. The following is not an exhaustive list but does illustrate the expansion in the science of microscopy which began earlier this century and which continues today. First came the use of electrons in the forms of transmission and scanning electron microscopies [TEM and SEM 3,4]. Then, relatively recently, came the use of sound as an imaging medium in the development of acoustic microscopy [5,6]. Most recently, near-field optical microscopy [7] and the family of scanning probe microscopies have been developed [8]. 

Dragnea, B., J. Preusser, W. Schade, S.R. Leone, and W.D. Hinsberg. 1999. Transmission near-field scanning microscope for infrared chemical imaging. J. Appl. Phys. 86 2795-2799. 

The first application of the SNOM for the MO studies happened in 1992 [62], when it was demonstrated that near-field MO observation can be obtained in the same manner as conventional far-field observation— that is, by using two cross-polarizers. Betzig et al. [62] visualized 100-nm magnetic domains and claimed spatial resolution of 30-50 nm. The possibility of MO domain imaging was confirmed in both the transmission regime (Faraday geometry) [63,64] and the reflection regime (Kerr microscopy) [65-67]. 

The next step was to improve the stability of the system and - even more importantly - to improve the transmission of the fiber tips. Metalization of the tip is the key and produces superior properties, such as a near-field spot of less than 20 nm [107-110]. Zeisel et al. reported that metalization led to optical transmission of a fiber higher than that of conventional fibers by several orders of magnitude [111]. The authors showed images based on the fluorescence of dye-labeled polystyrene spheres and noted that fast and irreversible photobleaching takes place in the near field with enhanced intensity. In addition, they reported on surface-enhanced near-field Raman spectra of cresol fast violet and p-aminobenzoic acid adsorbed on a (rough) silver substrate, exhibiting a signal-to-noise ratio of >10 [111]. 

Fig. 4.13 (a) Near-field transient transmission image of the nanorod taken at delay time of 600 fs. (b) Simulated transient transmission image of the nanorod. Dotted lines approximate shape of the nanorod. Scale bars 100 nm... 

Surface Lateral resolution, mapping/imaging Ear-field microscopy (reflection, transmission, polarised, fluorescence, phase-contrast, interference) near-field microscopy (AFM/SPM morphology, micro-roughness) elemental imaging... 

Fig. 2a-c. High resolution axial bright field transmission electron micrograph taken near Sherzer focus, for which the point-to-point resolution is = 2.5 A. The sam e consists of dispersed CdS crystallites on a thin carbon support film a an area containing several crystallites and demonstrating the size variational b, c magnified images of individual crystallites [7]... 

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