Keywords :
Theoretical or Mathematical, Experimental/ ab initio calculations; density functional theory; diamond; energy gap; nanoparticles; surface reconstruction; X-ray absorption spectra; X-ray emission spectra/ nanodiamond particles; quantum confinement; fullerenelike surface reconstructions; x-ray absorption; x-ray emission; ab initio calculations; optical gap; carbon clusters; bucky diamonds; soft x-ray fluorescence; 2 nm; 1 nm; C/ A7125W Electronic structure of solid clusters and nanoparticles A6146 Structure of solid clusters, nanoparticles, and nanostructured materials A6820 Solid surface structure A7115A Ab initio calculations (condensed matter electronic structure) A7115M Density functional theory, local density approximation (condensed matter electronic structure) A7870D X-ray absorption and absorption edges (condensed matter) A7870E X-ray emission threshold and fluorescence (condensed matter)/ size 2.0E-09 m; size 1.0E-09 m/ C/sur C /el
Abstract :
[en] We present x-ray absorption and emission experiments and ab initio calculations showing that the size of carbon diamond must be reduced to at least 2 nm, in order to observe an increase of its optical gap, at variance with Si and Ge where quantum confinement effects persist up to 6-7 nm. In addition, our calculations show that the surface of nanodiamond particles larger than sime 1 nm reconstructs in a fullerenelike manner, giving rise to a new family of carbon clusters: bucky diamonds. Signatures of these surface reconstructions are compatible with pre-edge features observed in measured absorption spectra
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