Electronic size effects

Cluster-Specific Mechanisms Electronic Size Effects... 

Electronic Size Effects. Understanding the size-dependent electronic structure of the Au /MgO(Fsc) model catalysts, which is fundamental for elucidation of their atom-by-atom controlled reactivity, is facilitated by analysis of the spectra of the LDOS projected on the oxygen molecule and on the metal cluster (see also Electronic Size Effects ). Figure 1.78a shows the LDOS projected on the O2 molecule which is adsorbed at the peripheral site (Fig. 1.77f) of the more reactive isomer of the Aug/MgO(F5c) model catalyst. As shown above, bonding and activation of O2 on the octamer is enabled by resonances formed between the cluster s electronic states and the 2jt molecular states... 

Electronic size effects Varying electronic structure as a function of cluster size. 

Rossetti R, Nakahara S and Brus L E 1983 Quantum size effects In the redox potentials, resonance Raman spectra and electronic spectra of CdS crystallites In aqueous solution J. Chem. Phys. 79 1086... 

Rossetti R ef al 1984 Size effects In the excited electronic states of small colloidal CdS crystallites J. Chem. Phys. 80 4464... 

Quantum efficiencies Quantum efficiency Quantum electronics Quantum fluids Quantum mechanics Quantum size effect Quantumwell... 

Band gap engineetring confined hetetrostruciutres. When the thickness of a crystalline film is comparable with the de Broglie wavelength, the conduction and valence bands will break into subbands and as the thickness increases, the Fermi energy of the electrons oscillates. This leads to the so-called quantum size effects, which had been precociously predicted in Russia by Lifshitz and Kosevich (1953). A piece of semiconductor which is very small in one, two or three dimensions - a confined structure - is called a quantum well, quantum wire or quantum dot, respectively, and much fundamental physics research has been devoted to these in the last two decades. However, the world of MSE only became involved when several quantum wells were combined into what is now termed a heterostructure. 

P-10 gas, 45, 219 Pair production, 290 Palladium, determination by x-ray emission spectrography, 328 Particle size, effect of variations of, in mineral analysis, 200 Philips Autrometer, 252-256, 280 Philips Electronics gas analyzer, 135 Philips Electronics improved Coolidge tubes, 248, 252, 253... 

The turnover frequency (TOP) based on surface-exposed atoms significantly increases with a decrease in the diameter of the gold particle from 5 nm [66]. This feature is unique to gold, because other noble metals usually show TOFs that decrease or remain the same with a decrease in the diameter [7]. The decrease in particle size gives rise to an increase in corner or edge and perimeter of NPs and change in electronic structure however, the origin of size effects on catalytic activity for CO oxidation is not clear. 

Rossetti R, Ellison JL, Gibson JM, Bms LE (1984) Size effects in the excited electronic states of smaU coUoidal CdS crystaUites J Chem Phys 80 4464 469... 

An apparent particle size effect for the hydrodechlorination of 2-chlorophenol and 2,4-dichlorophenol was observed by Keane et al. [147], Investigating silica supported Ni catalysts (derived from either nickel nitrate or nickel ethane-diamine) with particles in the size range between 1.4 and 16.8 nm, enhanced rates for both reactions were observed with increased size over the full range (Figure 13). As electronic factors can be ruled out in this dimension, the observed behavior is traced back to some sort of ensemble effect, known from CFC transformations over Pd/Al203... 

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