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 Cn 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 (CnH2). 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.