Electronic Properties of Nanodiamond

Examining the electronic properties of nanodiamond turns out to be rather complicated by the variable sample quality and the associated differences in the electronic structure, so in this chapter, just some important aspects of electronic properties and structure will be discussed. For a more detailed presentation refer to the respective original literature given in the appendix. 

Contrary to the bulk material there are also sp -hybridized regions in nanodiamond. In particular, they are situated on the particle surface. This graphitic portion 

Particularities like unpaired electrons at unsaturated bonding sites play a role for the electronic properties too, of course. However, a spin density of only 10 -10 spins per gram is determined from respective measurements (Section 5.4.1.5), which corresponds to a one-digit number of spins per nanodiamond particle. It results from a strong tendency toward saturation by the formation of re-bonds. In doing so, surface states rather graphitic in character are formed that cause, among other effects, also an electric conductivity (see below). 

The electronic structure of a nanodiamond sample may be examined by various spectroscopic techniques. Depending on the choice of method, the information obtained from doing so corresponds to different depths of the lattice. The Auger spectroscopy, for instance, has a low penetration depth, so it may serve to determine the situation of n-electrons on the surface. In the Cls-loss spectrum, on the other hand (Section 5.4.1.3), no 7i-transitions are observed as this method chiefly yields information on the second to seventh layer of atoms below the surface. 

For various samples of nanodiamond, conductivity measurements have also been made. The degree of graphitization plays a major role here for the magnitude of resistance. On suitably purified nanodiamond particles, there are initially just small, incoherent ti-systems, and the conjugation is anything but pronounced. 

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