Charge resonance enhanced ionization of CO2 probed by laser Coulomb explosion imaging

• Published in: Physical review letters 2011-08, Vol.107 (6), p.063201-063201
• Main Authors: Bocharova, Irina, Karimi, Reza, Penka, Emmanuel F, Brichta, Jean-Paul, Lassonde, Philippe, Fu, Xiquan, Kieffer, Jean-Claude, Bandrauk, André D, Litvinyuk, Igor, Sanderson, Joseph, Légaré, François
• Format: Article
• Language: English
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.107.063201

The process by which a molecule in an intense laser field ionizes more efficiently as its bond length increases towards a critical distance R(c) is known as charge resonance enhanced ionization (CREI). We make a series of measurements of this process for CO(2), by varying pulse duration from 7 to 200 fs, in order to identify the charge states and time scales involved. We find that for the 4+ and higher charge states, 100 fs is the time scale required to reach the critical geometry ≈ 2.1 Å and ≈ 163° (equilibrium CO(2) geometry is ≈ 1.16 Å and ≈ 172°). The CO(2)(3+) molecule, however, appears always to begin dissociation from closer than 1.7 Å indicating that dynamics on charge states lower than 3+ is not sufficient to initiate CREI. Finally, we make quantum ab initio calculations of ionization rates for CO(2) and identify the electronic states responsible for CREI.