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The functionalization of small diameter (ca. 50 nm) polycarboxylated nanodiamond particles using amide coupling methodologies in both water and acetonitrile solvent has been investigated. In this manner, the surfaces of nanodiamond particles were adorned with different luminescent moieties, including a green fluorescent 1,8-naphthalimide species (Nap-1), and a red emitting ruthenium(II) tris-bipyridine complex (Ru-1), as well as dual functionalization with both luminophores. Comprehensive characterization of the surface functionalized nanodiamonds has been achieved using a combination of dynamic light scattering, nanoparticle tracking analysis, transmission electron microscopy, X-ray photoelectron spectroscopy, zeta potential measurements, microwave plasma atomic emission spectroscopy and time-resolved photophysics. The tendency of the functionalized nanodiamonds to aggregate reflects the degree of surface substitution, yielding small aggregates with typical particle sizes ca. 150 nm. This is likely to be driven by the reduction of the zeta potential, concomitant with the conversion of surface charged carboxylate groups to neutral amide functions. The results show that luminescent nanodiamond materials can be synthesised with tuneable photophysical properties. Image 1 [ABSTRACT FROM AUTHOR]

The chemical nature of the chemical mechanical polishing of diamond has been examined by adding various redox agents to an alkaline SF1 polishing slurry. Three oxidizing agents, namely hydrogen peroxide, potassium permanganate and ferric nitrate, and two reducing agents, oxalic acid and sodium thiosulfate, were added to the SF1 slurry. Oxalic acid produced the fastest polishing rate while hydrogen peroxide had very little effect on polishing, probably due to its volatile nature. X-ray photoelectron spectroscopy (XPS) reveals little difference in the surface oxygen content on thesamples polished using various slurries. This suggests that the addition of redox agents do not increase the density of oxygen containing species on the surface but accelerate the process of attachment and removal of Si or O atoms within the slurry particles to the diamond surface. [ABSTRACT FROM AUTHOR]

In this paper, the reaction dynamics of hydrogen termination of nanodiamond annealed at low temperature (500 °C) in molecular hydrogen atmosphere is reported. In-situ residual gas analysis of nanodiamond particles (4–5 nm) during annealing/hydrogenation indicates C 3 -radical desorption which incites a free radical reaction through the reduction of molecular hydrogen to atomic hydrogen. Consequently, as released atomic hydrogen facilitates C H adsorption on the surface of nanodiamond which was confirmed using infrared spectroscopy. This explains how nanodiamond particles can play a key role in hydrogen (H 2 ) dissociation and be terminated by the hydrogen (H) at relatively low temperature. [ABSTRACT FROM AUTHOR]

Fluorinated nanodiamonds are considered for the fabrication of diffusive slow-neutron reflectors of a new kind. Hard fluorination of nanodiamonds drastically reduces the neutron absorption, thus providing an unprecedented albedo for the reflection of slow neutrons, bridging the so-called reflectivity gap in the neutron spectrum. The resulting reflectors can dramatically improve the performance of neutron sources, the efficiency of neutron delivery, and thus fluxes at neutron instruments. They open the way to the design of a new generation of neutron sources and experiments. [ABSTRACT FROM AUTHOR]