Theoretical study on the thermodynamic and transition properties of the interstellar molecule: FeC

Abstract

As an interstellar molecule, the thermodynamic properties and transition characteristics of FeC hold significant importance. In this study, high-precision ab initio methods were employed to obtain the potential energy functions of the five Λ-S states of FeC. Based on these results, the Partition functions, proportions of each molecular and thermodynamic properties were calculated for temperatures from 50 K to 10,000 K. In addition, the spin orbit coupling effects on the ground state (X ³Δ) split it into three Ω states (Ω = 3, 2, 1), with Ω = 3 being the lowest. The rotational spectrum for Ω = 3 at 298.15 K shows significantly higher transition intensity for the v′ = 0 and v′′ = 0 band. Moreover, this paper presents the ultraviolet spectrum of two transitions: X ³Δ ↔ 1³Π and 1³Π ↔ 1³Σ⁻, at a temperature of 298.15 K, with the 1³Π ↔ 1³Σ⁻ transition having stronger absolute intensity.