High-resolution study of oscillator strengths and predissociation rates for ¹³C¹⁸O

W-X bands and Rydberg complexes between 92.9 and 93.5 nm

¹ Observatoire de Paris, LERMA, UMR 8112 du CNRS, 75014 Meudon, France
e-mail: michele.eidelsberg@obspm.fr
² Institut des Sciences Moléculaires d’Orsay (ISMO), CNRS – Université Paris-Sud (UMR 8214), 91405 Orsay, France
e-mail: jean-louis.lemaire@u-psud.fr
³ Department of Physics and Astronomy. University of Toledo, Toledo, OH 43606, USA
e-mail: steven.federman@utoledo.edu
⁴ Leiden Observatory, Leiden University, 2300 RA Leiden, The Netherlands
⁵ Department of Physics, Wellesley College, Wellesley, MA 02481, USA
⁶ School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85281, USA
⁷ Université Versailles St-Quentin; Sorbonne Universités, UPMC Université Paris 06; CNRS/INSU, LATMOS-IPSL, 78280 Guyancourt, France
⁸ DESIRS beamline, Synchrotron SOLEIL, 91192 Saint-Aubin, France

Received: 5 December 2016
Accepted: 25 January 2017

Abstract

We carried out experiments at the SOLEIL synchrotron facility to acquire data for modelling CO photochemistry in the vacuum ultraviolet. We report oscillator strengths and predissociation rates for four vibrational bands associated with transitions from the v = 0 level of the X ground state to the v = 0–3 vibrational levels of the core excited W¹Π Rydberg state, and for three overlapping bands associated with the 4pπ, 5pπ, and 5pσ Rydberg states between 92.9 and 93.4 nm in ¹³C¹⁸O. These results complete those obtained in the same conditions for ¹²C¹⁶O, ¹³C¹⁶O, and ¹²C¹⁸O recently published by us, and extend the development of a comprehensive database of line positions, oscillator strengths, and linewidths of photodissociating transitions for CO isotopologues. Absorption spectra were recorded using the Vacuum UltraViolet Fourier Transform Spectrometer (VUV-FTS) installed on the Dichroïsme Et Spectroscopie par Interaction avec le Rayonnement Synchrotron (DESIRS) beamline at SOLEIL. The resolving power of the measurements, R = 300 000 to 400 000, allows the analysis of individual line strengths and widths within the bands. Gas column densities in the differentially pumped system were calibrated using the B-X (0–0) band at 115.1 nm in ¹³C¹⁸O.