Laser-ablation experiments with metals provide a source of electrons for capture processes, which are codeposited with solid argon and neon containing molecular fluorine. New argon and neon matrix absorptions at 510.6 and 524.7 cm⁻¹, respectively, are photosensitive upon irradiation at >290 nm, which is consistent with their assignment to an isolated anion. These bands are below the [M]⁺[F₃]⁻ antisymmetric trifluoride stretching frequency of 550 cm⁻¹ in an argon matrix, which is the typical relationship for cation−anion complexes and matrix-isolated anions. Thus, we report the isolated [F₃]⁻ anion in solid argon and neon environments. Moreover, we have carried out quantum-chemical calculations up to and including the CCSD(T) method to investigate the stabilities of polyfluoride anions higher than the [F₃]⁻ anion.