Side-illuminated

Pettinger et al. observed TERS with a sharp Au tip for MGITG dye on Au(l 11) with a side illumination [28]. They studied the bleaching of the dye and fitted the data by taking into account the radial varying intensity distribution of the field as a Gaussian profile instead of a Heaviside profile. For the former profile, the TERS radius is smaller by a factor of 1/2 than for the latter profile. They obtained a TERS enhancement factor of 6.25 x 10. The radius of the enhanced field Rfieid is about 50 nm, which results in a TERS radius of 25 nm, which is smaller than the radius of the tip apex (about 30 nm). 

In the case of one-sided illumination of a strongly absorbing sphere, the photophoretic force for the slip-flow regime is given by (Reed, 1977)... 

Mehtani, D., Lee, N., Hartschuh, R. D., Kisliuk, A., Foster, M. D., Sokolov, A. P, and Maguire, J. F. 2005. Nano-Raman spectroscopy with side-illumination optics. J. Raman Spectrosc. 36 1068-75. 

The excitation light for LAPS devices may be directed to the semiconductor either through the transparent insulator (front-side illumination) or from the opposite side of the planar structure (back-side illumination) by placing one or more light sources just below the semiconductor. If front-side illumination is used, the injection of... 

All the results were confirmed by investigations with both back- and front-side illumination [37]. In this study, which also describes theoretical aspects, a final resolution of 17 pm for an epi-structure was achieved, which consisted of a thin layer (3 pm, specific resistance of lOQcm) and a thick silicon substrate (0.38 pm, with low specific resistance of 0.005-0.02 Q cm). Instead of using a pattern grid on the front-side to study the smallest possible resolution, in this work the sensor chip was coated half with a metal layer. This forms on the covered side a metal-insulator-semiconductor (MIS) structure. The light pointer was moved from the metallised area to the uncovered area and the resolution was determined at the borderline by measuring the photocurrent that depends on the diffusion length of the carriers. Since, for the assumption that the diffusion length is the main decisive and critical parameter for the amount of carriers which could reach the metal-covered part of the semiconductor substrate from a specific distance, the calculation of the minimal resolution was experimentally observed. 

Front-side illumination on bulk material (300-400 pm) 100 Test pattern [35]... 

Front- and back-side illumination of an epi-layer structure 17 Average diffusion length [37]... 

Smaller sizes of particles (and for a polydisperse cloud, more particles) will be seen when the particles are viewed between the light source and the observer than when viewed with side illumination. This observation can be confirmed easily by comparing the number of... 

The above result was obtained with front-side illumination geometry. As one would intuitively expect, carrier collection is most efficient close to the rear contact. Indeed, marked differences have been observed for photoaction spectra with the two irradiation (i.e., through the electrolyte side vs. through the transparent rear contact) geometries for Ti02, CdS and CdSe nanocrystalline films [319, 342]. Obviously, the relative magnitudes of the excitation wavelength and the film thickness critically enter into this variant behavior. 

Figure 17. Effect of front side and back side illumination of semiconductor electrodes coated with phthalocyanine thin films. The direction of the photocurrent could be controlled by illumination direction and the redox couple in the solution.

For particle sizes in excess of 20 nm, side illumination produces the Tyndall effect. Particles about 200 nm in size cause opalescence in transmitted light the glass appears yellow, in reflected light bluish (so-called opalines). Opal glasses show a milky... 

HO, ratio of the length to the diameter of the curved pore bottom. B.iUu., back side illuminated F.illu, front side illuminated. 

Akhremitchev et al. presented a set-up based on the same principle, namely 1R s-SNOM with a side-illuminated AFM tip, and employed it to characterize nano-structured polymer blends that were used as minimally adhesive surface coatings to prevent biofouHng [57, 58]. Raschke ct al. used sharp Au-coated, forward-pointing ( nose-type ) AFM probes with a radius of 10-15 nm, and obtained fixed-... 

Along with the methods based on investigation of the scattering of light by disperse system as a whole, there are also methods based on the scattering (the diffraction) of light on individual particles. One of such methods, ultramicroscopy, played an important role in the development of colloid science. Dark field optical systems, ultramicroscopes, and dark field condensers, such as those utilized in optical microscopes for side illumination,... 

Aerosols can experience external influences induced by forces other than electrical or gravitational fields. For example, more than a century ago it was observed by side illumination that next to a heated object there is a layer containing practically no aerosol particles. The thickness of this layer was found to increase with the temperature of the object. In our discussion so far, we have assumed that the fluid in which our particles are suspended is homogeneous without temperature or gas concentration gradients, and so on. Under these conditions there is no preferential direction for the bombardment of the particle by fluid molecules. However, when there are gradients in the fluid temperature, concentration, and so on, there are differences in momentum imparted to a particle by molecules coming from different directions, producing a directional preference in the Brownian diffusion. 

Fig. 10.22 TERS set-up for side illumination of tip and sample using the 60 arrangement. Olympus long distance microscope 50x magnification, NA=0.5. He-Ne laser 5 mW at the sample. X =632.S nm. (Reprinted with permission from Ref [143].)...

Figure 1.32 Illumination geometry used to study type conversion of CdTe layers on CdS. SS, substrate side illumination ES, electrolyte side illumination.

Figure 1.35 EQE spectra for substrate side illumination for CdTe films on CdS/FTO that have been annealed for different times. The spectra show that formation of the p-n junction requires at least 5 minutes annealing time.

Schematic diagram of back-side illumination electrochemical etching technique.

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