Infrared spectra of Rg1,2-C6H6 complexes, Rg = He, Ne, Ar

Highlights: • Supersonic jet infrared spectra of rare gas – benzene dimers and trimers. • Probed using rapid-scan optical parametric oscillator source. • First infrared observations of rare gas – C₆H₆ complexes. • First spectroscopic observations of Ne₂ – C₆H₆ and He – Ne – C₆H₆. • Four bands analyzed for each species: ν₁₂ itself and three linked combinations. Infrared spectra of Rg_1,2 - C₆H₆ complexes (Rg = He, Ne, Ar) are observed in the region of the ν₁₂ fundamental of C₆H₆ using a pulsed supersonic jet expansion and a tunable optical parametric oscillator laser source. The mixed trimer He - Ne - C₆H₆ is also detected. Four bands are analyzed for each complex, namely ν₁₂ itself (≈3048 cm⁻¹) and three linked combination bands (≈3079, 3100, and 3102 cm⁻¹). The results are consistent with previous ultraviolet and microwave results, with Ne₂ - C₆H₆ and He - Ne - C₆H₆ being analyzed spectroscopically here for the first time.