O 1s excitation and ionization processes in the CO2 molecule studied via detection of low-energy fluorescence emission

• Published in: Journal of physics. B, Atomic, molecular, and optical physics Atomic, molecular, and optical physics, 2011-08, Vol.44 (16)
• Main Authors: KIVIMÄKI, A, ALVAREZ-RUIZ, J, WASOWICZ, T. J, CALLEGARI, C, DE SIMONE, M, ALAGIA, M, RICHTER, R, CORENO, M
• Format: Article
• Language: English
• Subjects: Atomic and molecular physics; Autoionization, photoionization, and photodetachment; Exact sciences and technology; Fluorescence and phosphorescence spectra; Fluorescence and phosphorescence; radiationless transitions, quenching (intersystem crossing, internal conversion); Molecular properties and interactions with photons; Photon interactions with molecules; Physics
• ISSN: 0953-4075; 1361-6455
• DOI: 10.1088/0953-4075/44/16/165103

Oxygen 1s excitation and ionization processes in the CO 2 molecule have been studied with dispersed and non-dispersed fluorescence spectroscopy as well as with the vacuum ultraviolet (VUV) photon- photoion coincidence technique. The intensity of the neutral O emission line at 845 nm shows particular sensitivity to coreto-Rydberg excitations and core-valence double excitations, while shape resonances are suppressed. In contrast, the partial fluorescence yield in the wavelength window 300-650 nm and the excitation functions of selected O + and C + emission lines in the wavelength range 400-500 nm display all the absorption features. The relative intensity of ionic emission in the visible range increases towards higher photon energies, which is attributed to O 1s shake-off photoionization. VUV photon - photoion coincidence spectra reveal major contributions from the C + and O + ions and a minor contribution from C 2+. No conclusive changes in the intensity ratios among the different ions are observed above the O 1s threshold. The line shape of the VUV - O + peak carries some information on the initial core excitation.