Comparison between photoemitting and colloidal properties of nanodiamond particles

In this paper, we present an investigation on two types of nanodiamond (ND) powders with average size of particles around 250 nm and having different sp(2) (graphite phase) and sp(3) (diamond phase) carbon contents. The ND surface modification is carried out by physical methods i.e. treatments in H-2 microwave plasma. The quantum efficiency (QE) of photocathodes and the stability of aqueous dispersions are assessed by photoemission and zeta potential (ZP) measurements, respectively. The resultant hydrogenated surface affects in the solid state the QE of ND-based photocathodes and in solution the particle ZP. The effect of the hydrogen treatment is beneficial inducing an enhancement of photocathode QE and a corresponding increase of the ZP. A schematized energy diagram is proposed to illustrate and explain the strong correlation between QE and ZP parameters.