Nanopartides size dependence

Gold nanostructures of various sizes and morphologies were synthesized at room temperature using naturally occurring biodegradable plant surfactants [ 76]. The sizes and shapes (spherical, prisms, and hexagonal) of the synthesized nanopartides were dependent on the concentration of the gold ions and the type of plant surfactant used for preparation. 

Colloidal metal nanopartides may have optical absorption spectra with an absorption peak that resembles that of colloidal semiconductor particles (cf. Figure 2.11 and Figure 2.13). However, this absorption does not derive from transitions between quantized energy states. Instead, in metal partides the collective modes of motion of the electron gas may be exdted, and these are referred to as surface plasmons [122,123]. The peak in the absorption spectrum is the resonance frequency for the generation of surface plasmons. The size-dependence of the plasmon frequency is... 

Metal nanopartides are attractive catalytic materials because of their high surface area to volume ratio and their size-dependent... 

Fig. 6.3 (a) Preparation process of 3-mercaptopropionic acid stabilized gold nanopartides by citrate-reduction, (b) The particle sizes depend on the stabilizer/gold ratios [28]... 

Due to their small size, nanoparticles have a very high specific surface area and dispersion, the latter being defined as the ratio of the number of surface atoms to the total number of atoms in the particle. Platinum particles with 2 nm diameter, e.g., have a surface area of 140 mVg and a dispersion of 50 %. Note that also the relative concentration of atoms located at corners, edges, and faces is strongly size dependent (Fig. These surface atoms are not equivalent to each other and frequently play different roles in catalysis. In the following, we focus on metal nanoparticles,[ -ioi as one can find good reviews about metal oxide [n-i6] and semiconductor [17-23] nanopartides elsewhere. 

Jani, P., Halbert, G.W., Langridge, J. and Florence, A.T. (1990) Nanopartide uptake by the rat gastrointestinal mucosa quantitation and partide size dependency. The Journal of Pharmacy and Pharmacology, 42(12), 821-5. 

Gold nanopartides (Au NPs) work as catalysts for organic reactions, and have been studied extensively over the world.However, ready aggregation of Au NPs in solution had been a problem for practical use. Therefore, the Au NPs should be covered with polymeric or small organic molecules. The fine dispersion (or solution) of Au NPs was obtained according to simple procedures invented by Tsunoyama et and Sakurai et and size dependence of cata-... 

Darugar, Q., Qian, W., El-Sayed, M.A. and Pileni, M.P. (2006) Size-dependent ultrafast electronic energy relaxation and enhanced fluorescence of copper nanopartides. The Journal of Physical Chemistry B, 110,143-9. 

Haynes, C.L. and Van Duyne, R.P. (2001) Nanosphere lithography a versatile nanofabrication tool for smdies of size-dependent nanopartide optics. Journal of Physical Chemistry B, 105, 5599-611. 

Link, S. and El-Sayed, M.A. (1999) Size and temperature dependence of the plasmon absorption of colloidal gold nanopartides. Journal of Physical Chemistry B, 103 (21), 4212—4217. 

Metallic nanoparticles have been synthesized in vivo using plants. Intracellular synthesis of gold nanopartides was demonstrated using the sweet desert willow (Chilopsis linearis) plant [95]. The average size of Au nanopartides formed in various tissues was dependent on the concentration of Au in the respective tissues. Haver-kamp et al. [96] synthesized a gold-silver-copper alloy in vivo using the Brasskajuncea plant. 

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