Laser ablation of Ga in dielectric breakdown of gaseous hydrocarbons: deposition of ambient-pressure unstable Ga nanophases in carbonaceous environment

Abstract

IR laser-irradiation of Ga in gaseous hydrocarbon (benzene, ethyne or n-hexane) results in ablation of Ga and adjacent dielectric breakdown (DB) in gaseous hydrocarbons. These processes lead to chemical vapor deposition of Ga nanoparticles-containing carbonaceous films. Volatile products of DB were examined by FTIR spectroscopy and GC and GC/MS techniques and revealed as arising from carbonization reactions in the gas phase. The solid products were analyzed by FTIR, X-ray photoelectron and Raman spectroscopy and electron microscopy and disclosed as Ga nanophases enveloped by graphite-like shell of carbonaceous phase. These nanophases include ambient pressure stable orthorhombic and amorphous structures and tetragonal, cubic and rhombohedral structures that have been previously observed only at high pressures. The reported procedure of chemical vapor deposition of the high-pressure Ga nanostructures thus represents a novel approach to these phases.