The irradiation of linear chain alkanes in the liquid phase is shown to be an efficient method for the formation of a variety of polyyne, CnH2, species. The chemical products remaining in liquid octane, C8H18, after irradiation with 100 fs 800 nm laser pulses from a Ti:Sapphire laser system have been characterized using surface-enhanced Raman spectroscopy (SERS) and time of flight mass spectrometry (TOFMS). A reaction mechanism is proposed to explain the formation of long chain polyynes from the chemical products created during irradiation. This putative reaction sequence provides an explanation for the generation of polyynes incorporating more carbon atoms than present in the parent alkane.