High resolution absorption cross-section measurements of the Schumann–Runge bands of O2 by VUV Fourier transform spectroscopy

Abstract The photoabsorption spectrum of the O 2 Schumann–Runge bands was measured with resolution comparable to the Doppler widths by using the VUV Fourier transform spectrometer from Imperial College, London, combined with synchrotron radiation as a continuum light source at the Photon Factory, KEK, Japan. The analysis of the (12,0)–(17,0) bands of the Schumann–Runge system provides accurate rotational line positions as well as the line intensities from 185 to 175 nm. Molecular constants of the v ′ =12 to 17 levels of the B 3 Σ u − state have been determined. The ( v ′ ,0) band oscillator strengths were determined as 2.38, 2.62, 2.70, 2.66, 2.40, and 2.12×10 −5 for the bands from v ′ =12 to 17, respectively.