Polyacetylene formation under simulated circumstellar conditions

Carbon-chain molecules serve as precursors for complex molecules in the interstellar medium and act as indicators of both current physical conditions and past evolutionary trends. They hold significant importance in interstellar chemistry. Although typical carbon-chain molecules like polyacetylene (C ₄ H ₂ , C ₆ H ₂ ) have been observed in the IRC + 10216 star and CRL618 nebula, the formation mechanism of longer carbon-chain polyacetylenes remains under investigation. The development of an ultra-high-temperature pyrolysis photoionization time-of-flight mass spectrometer (UT-Py-PI-TOFMS) in laboratory astrophysics simulation experiments provides insights into the formation process of interstellar molecules. Detection of a range of long-chain polyacetylene molecules (up to 16 carbon atoms) in this instrument indicates that rapid radical reactions of ^• C _2n H with unsaturated hydrocarbons govern the growth process of long-chain polyacetylenes. These findings offer compelling evidence for the formation of carbon-chain molecules in space. Furthermore, this experiment successfully reproduces other interstellar molecules such as fullerenes.