Probing the electronic density of states of germanium nanoparticles: A method for determining atomic structure

We present first principles electronic structure calculations and photoemission measurements of the change in the valence band DOS of germanium as its dimensions are reduced from the bulk to the nanoscale. By comparing the calculated broadening of the s and s-p band peaks and the energy of surface dangling bonds to the measured DOS, we identify the most likely structure of these nanoparticles. We propose that, in contrast to recent interpretations, small 2-3 nm germanium nanoparticles prepared by gas-phase aggregation have a distorted diamond structure core due to effects of thermal reconstructions of the surface.