Photoion-yield study of the 3p-3d giant resonance excitation region of isolated Cr, Mn and Fe atoms

• Published in: Journal of physics. B, Atomic, molecular, and optical physics Vol. 45; no. 22; pp. 225204 - 225215
• Main Authors: Osawa, T, Kawajiri, K, Suzuki, N, Nagata, T, Azuma, Y, Koike, F
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 28.11.2012; Institute of Physics
• Subjects: Atomic and molecular physics; Atomic properties and interactions with photons; chromium; Exact sciences and technology; giant resonance; iron; manganese; photoion-yield spectrum; photoionization; Photoionization of atoms and ions; Photon interactions with atoms; Physics; Chromium Atoms; Photoelectron; Multiple ionization; Photoionization; Rydberg states; Electronically excited state; Manganese Atoms; Iron Atoms; Excitation; Photoabsorption; Giant resonances; Synchrotron radiation
• ISSN: 0953-4075; 1361-6455
• DOI: 10.1088/0953-4075/45/22/225204

Using the charge-separated photoion-yield method combined with monochromatized synchrotron radiation, single (M+) and double (M2+) photoionization spectra in the 3p excitation region were observed for isolated atoms M = Cr, Mn and Fe. The relaxation processes of excited states to double ionization, as well as to single ionization, were considered with the help of existing photoabsorption and photoelectron data and some calculations of highly-excited states of M+ using the atomic code GRASP92. In the 3p→3d giant resonance region before the 3p→n(s, d) Rydberg series starts, the spectral features in the M2+ channel are similar to those in the M+ channel. The ratios M2+ M+ in this region are rather constant accordingly against the photon energy with values 0.045 ± 0.005 for Cr, 0.17 ± 0.03 for Mn and 0.30 ± 0.08 for Fe at the giant resonance. The increase in the M2+ M+ ratio with increasing the atomic number Z can be explained by the increasing contribution of two-step double ionization via highly-excited M+ states. It is expected that, at the 3p→3d giant resonance, the one-step double ionization process occurs within a few per cent of the entire decay.