VUV-synchrotron absorption studies of N2 and CO at 900Â K

- Novel hot cell heated up to 900 K used in VUV-FTS at synchrotron SOLEIL.
- Recorded N2 and CO spectra including high-J states up to J ∼ 50.
- N2 spectra analysis using coupled Schrödinger equations.
- Accurate deperturbation analysis of CO spectra.
- Results relevant in astrophysical or (exo-)planetary atmospheric physics.

Photoabsorption spectra of N2 and CO were recorded at 900 K, using the vacuum-ultraviolet Fourier-transform spectrometer at the DESIRS beamline of synchrotron SOLEIL. These high-temperature and high-resolution measurements allow for precise determination of line wavelengths, oscillator strengths, and predissociative line broadening of highly-excited rotational states with J up to about 50, and also vibrational hot bands. In CO, the perturbations of the A1Π-X1Σ+ vibrational bands (0,0) and (1,0) were studied, as well as the transitions to perturbing optically-forbidden states e3Σ-,d3Δ,D1Δ and a′3Σ+. In N2, we observed line shifts and broadening in several b1Πu-X1Σg+ bands due to unobserved forbidden states of 3Πu symmetry. The observed state interactions are deperturbed and, for N2, used to validate a coupled-channels model of the interacting electronic states. These data are appropriate for use in astrophysical or (exo-)planetary atmospheric applications where high temperatures are important and in future spectroscopic models of these molecules.