Perturbations in the A¹Π, v = 0 State of ¹²C¹⁸O Investigated via Complementary Spectroscopic Techniques

Abstract

The A¹Π(v = 0) level of ¹²C ¹⁸O has been reinvestigated using three different high-resolution spectroscopic methods: (1) 2 + 1′ resonance-enhanced multiphoton ionisation of the A¹Π − X¹Σ⁺(0, 0) band using narrowband lasers in a Doppler-free geometry; (2) Fourier-transform emission spectroscopy in the visible range probing the B¹Σ⁺ − A ¹Π(0, 0) band in a discharge; (3) Fourier-transform absorption spectroscopy in the vacuum-ultraviolet range measuring the A¹Π − X¹Σ + (0, 0) and B¹Σ⁺ − X¹Σ + (0, 0) bands at multiple temperatures ranging from 90 to 900 K. An effective-Hamiltonian analysis of A¹Π, v = 0 levels was performed up to J = 44 which quantitatively addresses perturbations by the e³Σ⁻(v = 1), d³Δ(v = 4), a′³Σ + (v = 9), D¹Δ(v = 0), and I¹Σ⁻(v = 0, 1) levels.