Formation of carbon clusters Cn(1 ⩽n⩽ 4) by laser vaporization of graphite and a study of their chemical reactivity by gas chromatography–mass spectrometry

Abstract

Experimental evidence for the formation of C₁, C₂, C₃ and C₄ carbon clusters by the laser vaporization of pure graphite in liquid and gaseous benzene environments has been obtained by using a gas chromatography (GC) coupled with mass spectrometry (MS) analysis system. A constant irradiance was chosen: 10¹⁰ W cm^–2. In the gaseous benzene phase, one aggregation process of C_n was noticeably more important than in the liquid benzene phase. Two types of laser reactions may be distinguished: the addition of carbon clusters to a phenyl radical and the aggregation of carbon clusters resulting in carbyne compounds (C_nH₂). The effect of the wavelength of the focused laser beam is also discussed. There are shown to be contributions from two major kinds of interaction: a thermal interaction for IR and visible irradiation, evidenced by formation of C₂ clusters and photoelectronic effects from UV photons, evidenced by a high concentration of toluene.