Two-dimensional colloidal crystal

FIG. 2 Two-dimensional colloidal crystal formed by a single layer of polystyrene spheres of diameter 3 /mi. The particles are initially suspended in water. The crystal is formed by confining the suspension between two glass plates and reducing the separation until it equals the diameter of particles. Here, one can see some typical features of crystals such as defects, fractures and vacancies. 

FIG. 11 Light diffraction pattern of a two-dimensional colloidal crystal with hexagonal structure such as the one shown in Fig. 2. 

E. Kumacheva, P. Garstecki, H. Wu, and G. M. Whitesides, Two-dimensional colloid crystals obtained by coupling of flow and confinement, Phys. Rev. Lett., 91,128301 [2003]. 

Figure 2. Schematic ilhistiatian of the nanoq)here lithography Cabricatioo technique. A small vohime of nanosphere solution is diop-coated onto the clean substrate. As die solvent evaporates, die nanoqiheres assemble into a two-dimensional colloidal crystal mask. The desired noble metal is then dqpodted in a hi vacuum thin film vapor deposition tem. In the last step of the sam de prqnratioii, the lift-off step, the nanospheres are removed by sonication in absolute ethanol.

Zhang, J. Li, Y. Zhang, X. Yang, B. Colloidal self-assembly meets nanofabrication From two-dimensional colloidal crystals to nanostructure arrays. Adv. Mater. 2010, 22,4249-4269. 

Bubeck R, Bechinger C, Neser S, and Leiderer P. 1999. Melting and reentrant freezing of two-dimensional colloidal crystals in confined geometry. Physical Review Letters 82 3364-3367. 

Manna, L., De Vittorio, M., Cingolani, R., and Arakawa, Y. (2008). Two-Dimensional photonic crystal resist membrane nanocavity embedding colloidal dot-in-a-rod nanocrystals. Nano Lett, 8,1 260-264. 

U. Gasser. Crystallization in three- and two-dimensional colloidal suspensions./. Phys. Cond. Matter, 21 203101, 2009. 

Chapter 8 presents evidence on how the physical properties of colloidal crystals organized by self-assembly in two-dimensional and three-dimensional superlattices differ from those of the free nanoparticles in dispersion. 

Owing to the simphcity and versatility of surface-initiated ATRP, the above-mentioned AuNP work may be extended to other particles for their two- or three-dimensionally ordered assemblies with a wide controllabiUty of lattice parameters. In fact, a dispersion of monodisperse SiPs coated with high-density PMMA brushes showed an iridescent color, in organic solvents (e.g., toluene), suggesting the formation of a colloidal crystal [108]. To clarify this phenomenon, the direct observation of the concentrated dispersion of a rhodamine-labeled SiP coated with a high-density polymer brush was carried out by confocal laser scanning microscopy. As shown in Fig. 23, the experiment revealed that the hybrid particles formed a wide range of three-dimensional array with a periodic structure. This will open up a new route to the fabrication of colloidal crystals. 

Another important method for photonic crystal fabrication employs colloidal particle self-assembly. A colloidal system consists of two separate phases a dispersed phase and a continuous phase (dispersion medium). The dispersed phase particles are small solid nanoparticles with a typical size of 1-1000 nanometers. Colloidal crystals are three-dimensional periodic lattices assembled from monodispersed spherical colloids. The opals are a natural example of colloidal photonic crystals that diffract light in the visible and near-infrared (IR) spectral regions due to periodic modulation of the refractive index between the ordered monodispersed silica spheres and the surrounding matrix. 

An inkjet printing of colloidal crystals was proposed by Frese et describing inkjet printing processes of monodispersed particles which are able to form two- or three-dimensional photonic crystals on the substrate surface by arranging in a closely packed lattice structure on the surface. The particle size was selected so that it will diffract light in the visible spectral region, i.e., particle size of 200-500 nanometers. In this work drop-on-demand inkjet printing techniques are utilized. 

In addition two-dimensional imaging of polarized light micrographs of fat samples may be employed to determine the fractal dimension. The general scheme to measure the microscopy fractal dimension of a colloidal fat crystal network is shown in Figure 17.24. 

The size-selective precipitation (SPP) was predominantly developed by Pileni [50c]. One example (SPP) is monodisperse silver particles (2.3 nm, 0= 15%), which are precipitated from a polydisperse silver colloid solution in hexane by the addition of pyridine in three iterative steps. Recently, Schmid [52a] has reported the two-dimensional crystallization of truly monodisperse AU55 clusters. Chromatographic separation methods have thus far proven unsuccessful because the colloid decomposed after the colloidal protecting shell had been stripped off [42a]. The size-selective ultracentrifuge separation of Pt colloids has been developed by Colfen [52b]. Although this elegant separation method gives truly monodisperse metal... 

Pieranski P (1980) Two-dimensional interfacial colloidal crystals. Phys Rev Lett 45(7) 569-572... 

Ye X, Qi L (2011) Two-dimensionally patterned nanostructures based on monolayer colloidal crystals controllable fabrication, assembly, and applications. Nano Today 6 608... 

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