Nanoparticles surfaces atoms relating

Nanoparticles are discrete nanometer (10 m)-scale assemblies of atoms. Thus, they have dimensions between those characteristic of ions (lO m) and those of macroscopic materials. They are interesting because the number of atoms in the particles is small enough, and a large enough fraction of them are at, or near surfaces, to significantly modify the particle s atomic, electronic, and magnetic structures, physical and chemical properties, and reactivity relative to the bulk material. Nanoparticle surfaces themselves may be distinctive. Particles may be terminated by atomic planes or clusters that are not common, or not found, at surfaces of the bulk mineral. These, and other size-related effects will lead to modified phase stability and changes in reaction kinetics. 

As discussed in Lopez-Haro et some differences in the thermodynamics of CO-Au adsorption may also be expected to occur between the gold single-crystal and oxide-supported nanoparticle surfaces. According to the literature, the energy of CO adsorption on gold may depend on variables like the coordination number of the surface atoms, ° modulations induced on the An nanoparticles by the nature or redox state of the oxide support - and even, as suggested by some authors, on quantum effects associated with the size of the nanoparticles. These differences will obviously determine the specific T-P q relation at the adsorption equilibrium. 

Although (15.1) and (15.2) hold strictly only for a liquid in equilibrium with its vapor, they have been commonly apphed also to solid materials, in particular for describing nanoparticle sintering (see the discussion in [Campbell et al., 2002]). However, a number of comphcations must be considered for solid materials. First of all, y cr, since for a sohd a change in the surface area A can be reahzed either by increasing the number of surface atoms without changing the interatomic distances between them (this is related to the first term in (15.3)) or by introducing a strain (this is related to the second term in (15.3)) ... 

Supported nanoparticles (1-1.5 nm) based on Ru4Pt2 entities have been obtained by using a Ru4Pt2(CO)i8 precursor on carbon black and fullerene soot [63]. XANES analysis showed differences between the interaction of nanoparticles with both carbon black and fullerene supports. In particular, a change in the electronic properties of the nanoparticles on fullerene is proposed this change was related to a strong interaction between the nanoparticle and a surface-atom, probably via the formation of a Ru-carbide phase. 

This chapter concerns composite films prepared by physical vapor deposition (PVD) method. These films consist of dielectric matrix containing metal or semiconductor (M/SC) nanoparticles. The structure of films is considered depending on their formation by deposition of M/SC onto dielectric substrates as well as by layer-by-layer or simultaneous deposition of M/SC and dielectric vapor. Data on mean size, size distribution, and arrangement of M/SC nanoparticles in so obtained different composite films are given and discussed in relation to M/SC nature and matrix properties. Some models of nucleation and growth of M/SC nanoparticles by the diffusion of M/SC atoms/molecules over a surface or in volume of dielectric matrix are proposed and analyzed in connection with experimental data. 

Kidd, Lennon and Meech [26] also studied the related process of photodesorption, finding that the photodesorption cross sections for NO and SO2 also exhibited peaks near the small particle surface plasmon resonance for silver. For an earlier study that also presents evidence for surface plasmon induced desorption, in this case desorption of atoms from the metal nanoparticles (composed of sodium) themselves, see Ref [27]. The review article by Watanabe et al. [12] also discusses some more recent results on plasmon induced desorption. 

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