Abstract
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•This paper indicates longer pollyne formations compared with starting alkane liquid by femtosecond laser irradiation.•Formation of pollynes by femtosecond laser irradiation of linear chain alkanes has been demonstrated by experimental data from time of flight mass spectrometry and Raman spectroscopy.•A chemical reaction mechanism has been proposed to explain longer pollyne chains present in the irradiated sample than the starter Octane molecule.•Laser focus acts as a generator for various charged ions, these ions initiate chemical reactions’ around laser focus few diffusion lengths away.
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.