UV and visible line spectra studies for plasma processing gases

UV and visible line spectra are essential tools for understanding of underlying physics of plasma. These spectra can be theoretically predicted using high-level electronic structure methods. Among various approaches, multireference configuration interaction (MR-CI) and equation-of-motion coupled-cluster (EOM-CC) are particularly suitable for modeling plasma processing gases and their ionic species. In this work, we focus on applicabilty of EOM-CC, which offers a good balance between accuracy and computational feasibility for molecules containing up to several tens of atoms.

Recently, we have developed a range of techniques within the EOM-CC framework that are particularly relevant to plasma spectroscopy, including a time-dependent formalism [1] and the evaluation of full second-order transition moments [2].

In this presentation, we demonstrate theoretical UV and visible spectral lines of key plasma processing gases. Diatomic molecules such as N₂ and O₂ are examined to assess the accuracy of the methods, while more complex species, including polyatomic molecules like CF_x and NF_x, are explored to demonstrate the method’s broader applicability. We also highlight the significant role of the non-dipole (multipole) contributions in shaping the spectral features of plasma gases.

[1] Y. C. Park, A. Perera, and R. J. Bartlett*, J. Chem. Phys. 151, 164117 (2019)

[2] Y. C. Park, A. Perera, and R. J. Bartlett*, J. Chem. Phys. 155, 094103 (2021)