Truncated tetrahedron particles

Recently, a new class of chemical and biological sensors has been developed based on the shift of the plasmon resonance wavelength that arises when the analyte of interest binds to the surface of the nanoparticle [9,38]. The effect is very much like that considered in Fig. 4.5, except that the particles considered are anisotropic (truncated tetrahedron shape), the particles are on a surface (glass or mica, typically) and the analyte layer thickness can be varied. Fig. 4.7 shows an example of the type of information studied, here showing the plasmon wavelength shift associated with binding many layers of molecules on the surface of the particle as a function of the layer thickness. The curves labeled B and D show results obtained in experimental studies for particles with dimensions 100 nm (in-plane) and 30 or 50 nm (out of plane), while curves A and C show calculated results for the same two structures. The molecules on the particle surface were... 

One reason for the behavior in Fig. 4.7 can be inferred from Figs. 4.8 and 4.9, in which we examine the electric fields near the particle surfaces. Fig. 4.8 shows contours of the field for the truncated tetrahedron particle, for light polarized along the z-axis in the figure. We see that the bottom tips of the particle are hot compared to the top and sides, with lEp being 12,000 at the tips, and only 6 on the cool sidewalls. Since the plasmon wavelength... 

Here, pseudo zero-dimensional platinum particles refer to those simple shapes such as spheres and highly symmetrical platonic shapes, including tetrahedrons, octahedrons, cubes, tetrahexahedrons (THHs), and their truncated forms [70, 75, 155]. Some transmission electron microscopy (TEM) images of faceted particles that have been recently obtained and categorized as pseudo-zero-dimensional nanostructures, due to their small size, symmetrical shape and single crystalHne nature, are shown in Figure 10.6. Typically, spherical nanoparticles are composed... 

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