Dimeric Nanoparticles

Enhanced electric-field distribution is illustrated schematically in Figure 3.8, based on reported electromagnetic simulations, for a dimer of a noble metal spherical nanoparticle. The optical field enhancement at the gap site occurs only when the incident polarization is parallel to the interparticle axis of the dimer. 

A key feature of PdCys as precursors of Pd(0) nanoparticles is that reduction of Pd(II) -> Pd(0) involving C-Pd bond cleavage is required. This accounts for both the high temperatures invariably required and the induction period in the absence of reductants. Rosner et al. have developed a detailed kinetic model of a Heck reaction catalyzed by dimeric palladacycles (Rosner et al. 2001 a,b). This model explains the experimental observations and is consistent with an active species... 

T. Haber, U. Schmitt, C. Emmeluth, and M. A. Suhm, Ragout jet FTIR spectroscopy of cluster isomerism and cluster dynamics From carboxylic acid dimers to N2O nanoparticles. Faraday... 

Hao E, Schatz GC (2004) Electromagnetic fields around silver nanoparticles and dimers. J Chem Phys 120 357-366... 

Figure 10.10. SEM micrographs of Ag nanoparticles. The images show (a) overview of the particles shapes and sizes, (b) Ag particle dimers after incubation in hemoglobin solution, and (c), (d) hot dimers and corresponding single-molecule SERS spectra. The double arrows in (c) and (d) indicate the polarization of the incident laser radiation. (With permission from Ref. 35.)...

In typical surface science experiments as presented previously, oxide-supported metal nanoparticles are deposited onto a clean oxide surface by physical vapor deposition. The precursor in this process is metal atoms in the gas phase, which impinge on the surface, diffuse until they eventually get trapped (either at surface defects or by dimer formation), and then act as nuclei for the growth of larger particles. These processes are well understood for ideal model systems under ultrahigh vacuum (UHV) conditions [56, 57]. In contrast, most realistic supported metal catalyst... 

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