Sp-hybridized carbon atoms formed by low-energy collisions in carbon nanofoams produced by pulsed laser deposition

Abstract

The appearance of an sp-hybridization signal has previously been reported in Surface-Enhanced Raman spectra of carbon nanofoams prepared by pulsed laser deposition (PLD). The details of the mechanism for the formation of the sp-hybridized carbon atoms need still further clarification. For a better understanding we have studied two samples produced by PLD in the same experimental run by placing one substrate in front of the plasma plume and a second one beside the graphite target. In this configuration the gas pressure is the same at both sites but the collision energies between the formed nanoparticles are very different. Our present results from Surface Enhanced Raman Spectroscopy and High-Resolution Transmission Electron Microscopy lead us to propose that the sp signal comes mostly from short carbon atom chains formed between carbon nanoparticles due to relatively low-energy collisions at deposition.