Direct synthesis of polyyne molecules in acetone by dissociation using femtosecond laser irradiation

Hydrogen-capped polyynes have been synthesized by 800 nm femtosecond photolysis of acetone molecules. Four bands appearing in the 1800–2200 cm⁻¹ range of surface enhanced Raman spectra show a mixture of polyynes with variable chain lengths in the irradiated acetone. The shortest hydrogen-terminated chain is found to be C₆H₂. The presence of charged carbon dimer, monomer C2+, C⁺ and double charged C²⁺ has been confirmed by time-of-flight mass spectroscopy. These ions are generated as irradiation products of stepwise dissociation of acetone and further act as building blocks in the synthesis of polyynes.