Marks decahedron

Figure 2 Schematic representation of a Marks-decahedron (111) (left) and (100) (right) projections. (From L.D. Marks [67].)...

Fig. 3.7. Most common stable shapes of nanoparticles (a) icosahedron, (b) truncated octahedon (Wulff shape), (c) Marks decahedron...

In experiments, the most common shapes have truncated vertices and correspond to particles named Marks decahedron and the round decahedron. 

The first structure [54] contains extra 111 facets and turns out to be quite stable. In particularly clean growth conditions (weak interactions with substrates), it results one of the predominant shapes for the size interval taken into account. An alternative way to describe the Marks decahedron is as a regular decahedron, which has truncations on its facets, as shown in Fig. 3.11 (3y, 3x and 3z). 

Fig. 19.4 Atomic configurations of a an fee dot of 9 shells with K — 3.3, b an fee rod of 3 shells with K = 1.9, and c an fee plate of AT = 1.7 thick, d an icosahedron with N]47 atoms, e a marks decahedron with Njoi, and f an fee truncated octahedron with N201 atoms (reprinted with...

Figure 3 Phase diagram of gold clusters as a function of their size. Ic icosahedron MTP, Dh decahedron MTP, SC single crystal, QM quasimelt, L liquid. (From P.M. Ajayan and L.D. Marks [77].)... 

Figure 3.11 Absorption and scattering spectra of an Ag regular decahedron (panels lx, ly, and Iz), a rounded decahedron (panels 2x, 2y, and 2z) and a Marks decahedra (panels 3x, 3y, and 3z), all with a 40 nm-side. The polarization direction is assumed to be parallel to the pentagonal motif and oriented along vertices E = (0,1, 0) in panels (a) and (b), parallel to the pentagonal motif and oriented along edges E = (0, 0,1) in panels (c) and (d], and perpendicular to the pantagonal motif E = (1, 0, 0) in panels (e] and (f).

In Fig. 3.11 we observe for the perpendicular polarization, that the optical response of the regular decahedron does not change for small truncations, in both cases, the Marks and rounded decahedra. For both parallel polarizations, the spectra of the truncated decahedra show differences with respect to the regular ones. The observed effects are similar to those already seen in the case of truncated cubes (Fig. 3.10) as a result of the increment of the faces, the main resonance is blue-shifted and its FWHM decreases. Finally, as for more regularly shaped nanoparticles, also for such kind of NPs the spectra show a red-shift with increasing size as a consequence of the radiation effects. 

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