Exploring Anthracene in Laser-Induced Carbon Plasma Studies with Long-Wave Infrared Laser-Induced Breakdown Spectroscopy for Understanding Carbon Microstructure Formation in Space

Abstract

Long-wave infrared laser-induced breakdown spectroscopy (LWIR LIBS) of anthracene, a representative polycyclic aromatic hydrocarbon, under high-energy plasma conditions, combined with harmonic and anharmonic emission spectral simulations and HITRAN-based analyses, uncovers potential pathways of molecular fragmentation, recombination, and intermediate formation, identifying small hydrocarbons (e.g., CH₄ and C₂H₂) and aromatic compounds (e.g., benzene and naphthalene). The experimental setup facilitated the simultaneous acquisition of UV/vis/NIR and LWIR spectra, offering a comprehensive analysis of molecular dynamics in a controlled plasma environment. Key findings demonstrate the influence of carrier gases, with argon inducing extensive fragmentation and helium maintaining the structural integrity of anthracene. Intriguingly, emission features at 6.98 and 8.3 μm suggest the possible presence of transient fullerenes, warranting further investigation. This study highlights the utility of LWIR LIBS for elucidating the fundamental mechanisms of cosmic carbon synthesis, offering insights into interstellar dust formation, planetary surface chemistry, and the pathways of prebiotic organic evolution. Future integration with mass spectrometry is proposed to enhance molecular identification and expand the understanding of plasma-induced carbon chemistry.