Diamond hydrogen-terminated

Figure 5.4. The highest occupied molecular orbital of a Si911,2 dimer cluster. The top two silicon atoms comprise the surface dimer, and the remaining seven Si atoms contain three subsurface layers which are hydrogen terminated to preserve the sp3 hybridization of the bulk diamond cubic lattice. The up atom is nucleophilic and the down atom is electrophilic.

Nichols, . M., Butler, J. E., Russell, J. N. and Hamers, R. J. Photochemical functionahzation of hydrogen-terminated diamond surfaces A structural and mechanistic study. Journal of Physical Chemistry 109, 20938 (2005). 

Diamond surfaces after anodic oxidation treatment involve oxygen-containing surface functional groups. The electron-transfer kinetics for ions and polar molecules are expected to be quite different. Fe(CN)l /4 was highly sensitive to the surface termination of diamond. For an anionic reactant, there was an inhibition of the electron transfer for the oxygen-terminated diamond electrodes compared with the hydrogen-terminated diamond electrodes, and there was also an acceleration of the electron transfer for oxygen-terminated diamond for some cationic reactants such as Ru(NH3) +/3+ and Fe2+/3+. These results can be explained by electrostatic effects, which interact between the ionic... 

Hydrogen-terminated boron-doped diamond (BDD) has emerged as a unique electrode material displaying, among other characteristics, extraordinary low chemical and electrochemical reactivity over a wide potential range allowing studies to be performed in PEO/Li salt solutions without interference from underpotential deposition, alloy formation and/or intercalation processes [67],... 

Figure 44 Schematic of the experimental arrangement for electrochemical measurements of hydrogen-terminated boron-doped diamond (BDD) films in a Li+-based solid polymer electrolyte in ultrahigh vacuum (UHV). (From Ref. 67.)...

C (lll)-H (diamond) (lxl) Hydrogen terminated diamond, sur- MEIS/2/ face layer spacing relaxed by -0.05 0.05 A. 

The hydrogen-terminated diamond surface also exhibits a p-type conduction. The surface structure, electronic properties, etc. have been extensively studied. This subject has a long history of research, and the readers can refer to Ref. [137] on this topic. Simply summarizing the results obtained so far, the thickness of the Surface conducting layer is 30-100 A, and the hole density at room temperature is approximately 10 /cm. ... 

In terms of science, it is expected that diamond still has some new properties that have never been exploited yet. Since the establishment of diamond CVD technology, the controlled doping for p- and n-type semiconductors, the presence of the ultrathin conducting layers of hydrogen-terminated surface, the negative... 

Surface reconstruction of diamond is described in Section 8. This section will just give additional information. Possible reconstructed structures of diamond (100) surface are shown in Figure D.l [139], where (a) and (b) are hydrogen-terminated, while (c) and (d) contain oxygen atoms. 

The possibility of diamond surface reconstruction without hydrogen termination has been discussed in Ref [461] based on an analogy with Si and Ge. The surface reconstruction models are Hanemann s (111) 2x1 buckling model [462], Tandy s (111) 2x1 model, Pandy s jr-bonded model [463], and Chadi s rr-bonded (111) 2 X 1 model [464]. It was suggested that the buckling and 7t-bonded structures are in equilibrium at temperatures above 1000 °C. In Ref [465], a reconstruction from an H-terminated (111) 1 x 1 to an H-free (111) 2 x 1 structures after heating at 1000 °C is described. 

Figure D.l. Possible reconstructed structures of diamond (100) surface, (a) unrelaxed surface with the dangling bonds being terminated by H atoms, (b) hydrogen-terminated 2 X 1 structure, (c) oxygen-terminated 2 x 1 structure, (d) single oxygen-terminated 2 x 1 structure, and (e) rt-bonded 2 x 1 structure [139],...

J. W. Mintmire and C. T. White, Simulations of Ceo Collisions with a Hydrogen-Terminated Diamond 111 Surface, J. Phys. Chem. 95, Xi92 ... 

Kubovic, M. Aleksov, A. Schreck, M. Bauer, Th. Stritzker, B. Kohn, E. Field effect transistor fabricated on hydrogen-terminated diamond grown on SrTiOs substrate and iridium buffer layer. Diamond Relat. Mater. 2003, 12, 403-407. 

Harrison et al. have considered indentation of nonmetallic systems including hydrogen terminated diamond [12,160]. Unlike the metal metal systems, diamond diamond systems did not show a pronounced jump to contact. This is... 

Depending on the method of their preparation, the individual nanodiamond particles do not exist as isolated crystallites, but they form tightly bound agglomerates. Apart from unordered sp - and sp -hybridized carbon, they may also include other impurities. The latter may originate either from synthesis or purification, for example, finely dispersed material from the reactor walls may contaminate the sample (Section 5.3). This is especially true for material produced by the detonation or shock wave method, whereas hydrogen-terminated diamond nanoparticles do not show this effect. 

Hydrogen-terminated diamond surface layer spacing relaxed by -0.05 0.05 A. 

In practice, these solid-vacuum interfacial energies are not likely to be seen, since the diamond surface and the graphite prism-face surfaces will reconstruct or react with adatoms such as hydrogen and oxygen to reduce their surface energy. Under atmospheric conditions, diamond is terminated by a range of hydride and oxide... 

Finally, when the BDD is removed from the CVD diamond reactor, it is hydrogen (H-) terminated, which also confers hydrophobic properties on the surface. Contact angles of 90 have been measured using water [34]. The question of how long the hydrogen termination lasts, especially after oxidative electrochemical treatment [4,17], is an important one to consider therefore at the minimum, simple contact angle verification before and after experiment is a necessary and important measurement to make. 

To extend the hydrogen evolution potential in an aqueous media, a fluorine-terminated diamond surface is prepared in a radio frequency plasma reactor of CF-He [124]. Fluorine-terminated diamond is usually used to study electrode reactions that require high over potential. For covalent attachment of different biomolecules, hydrogen-terminated diamond electrodes are also treated with ammonia plasma to prepare the surface with terminal amine groups [125]. 

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