CO2 laser-driven reactions in pure acetylene flow

TL;DR

This study demonstrates that a continuous wave CO2 laser induces self-sustained reactions in pure acetylene flow through multi-photon absorption, leading to the formation of carbon dimers and excited hydrogen, with implications for carbon allotrope synthesis and interstellar dust formation.

Contribution

It reveals a novel laser-driven reaction mechanism in pure acetylene flow involving multi-photon absorption and self-sustained reactions without oxygen.

Findings

Laser induces decomposition of intermediates to carbon dimers and excited hydrogen.

Reactions are self-sustained without oxygen, differing from thermal decomposition.

Potential applications in synthesizing carbon allotropes and understanding interstellar dust formation.

Abstract

We show that multiple-photon absorption of radiation from a 10.56 {\mu}m cw CO2 laser by intermediates (ethylene, vinylidene) generated in pure acetylene flow makes them decompose to carbon dimers and excited hydrogen. The latter associates with downstream acetylene to feedback those laser absorbing intermediates thus making the reactions self-sustained in the absence of oxygen. This process is different from acetylene self-decomposition that may occur at higher temperature and pressure. The results of our work may be useful for understanding the generation of various carbon allotropes and interstellar dust from acetylene.