The ground electronic state of ClF: Updated molecular constants and potential curves for ³⁵ClF and ³⁷ClF

A comprehensive assessment of available literature spectroscopic data and molecular constants for the X ¹Σ⁺ ground electronic states of isotopologues ³⁵ClF and ³⁷ClF is undertaken. Three different approaches are employed in the analysis of the available information. The first approach involves merging molecular constants from various studies to yield an optimized set of Dunham coefficients {Y₀₁, Y₀₂, Y₀₃, Y₁₀, Y₁₁, Y₂₁, Y₀₂ and Y₁₂}. Utilizing these updated constants, vibrational energies (G_υ) and rotational constants (B_υ) for υ = 0–9 are calculated, and RKR potentials are determined for both isotopologues. The second approach involves calculating synthetic spectroscopic line positions using literature molecular constants, with normally distributed random errors added on, and subjecting these to a modern direct-potential-fit analysis. This analysis produces a precise analytical potential energy function for ³⁵ClF, and Born-Oppenheimer breakdown functions that characterize adiabatic and non-adiabatic corrections. The third approach involves fitting the synthetic spectroscopic data directly to Dunham coefficients. The results of the three approaches are compared and discussed.