Single and double electron photodetachment from the oxygen anion at 41.7 nm

Harbo, L. S.; Becker, Andreas; Dziarzhytski, Siarhei; Domesle, Christian; Guerassimova, N.; Wolf, A.; Pedersen, H. B.

doi:10.1103/physreva.86.023409

Cited by 7 publications

(11 citation statements)

References 30 publications

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“…The interaction zone is located inside a structure of electrodes that can be individually biased and allows detailed control of the electric potential both along and transverse to the ion direction of motion. The emerging photofragments from the dissociation of H 2 O + were analyzed using three fragment detectors (DET1-3); the additional detectors for analysis of photoelectrons (eDET1-2) [53,54] were not exploited in this experiment. As illustrated in Fig.…”

Section: A Ion and Laser Beamsmentioning

confidence: 99%

Lifetime of low vibrational levels of the metastableB̃2B2state ofH2O+<

Harbo

Dziarzhytski²,

Domesle

et al. 2014

Phys. Rev. A

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The decay of metastable states of the water radical cation H 2 O + has been observed in an experiment that combines photofragment momentum imaging and electrostatic ion-beam trapping in a crossed-beam geometry. Photoabsorption of 532-nm laser light from a fast beam of H 2 O + is observed to yield fragmentation into both OH 0 + H + and OH + + H 0 . Using coincident photofragment momentum imaging, the initial state of the observed photofragmentation is associated with low vibrational levels of the second excitedB 2 B 2 state of H 2 O + , dissociating via absorption onto a repulsive part of theÃ 2 A 1 state. Electrostatic ion trapping in the laser interaction region is used to follow the photofragment intensity as a function of time and to determine the lifetime of the metastable states to be τB 2 B 2 = 198 ± 11 μs.

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Section: A Ion and Laser Beamsmentioning

confidence: 99%

Lifetime of low vibrational levels of the metastableB̃2B2state ofH2O+<

Harbo

Dziarzhytski²,

Domesle

et al. 2014

Phys. Rev. A

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“…By combining these measurements, background-corrected distributions of events from the ion-photon interaction only were obtained. In the present experiment, these electrodes were used both to extract photoelectrons perpendicular to the plane spanned by the incoming ion and photon pulses [28] and to analyze fragment identities through uniformly biasing the complete interaction region [29].…”

Section: A Ion and Photon Pulsesmentioning

confidence: 99%

“…While this analysis is relatively uncomplicated for coincidences among fragments registered on DET 1-3, photoelectron spectroscopy poses an experimental challenge in the present type of experiments, since electrons must be detected on a significant background of electrons resulting from ionization of the residual gas [28] which can saturate the detection system. Thus, the data obtained under conditions for photoelectron spectroscopy, i.e., with the saddle point configuration of the interaction region [see Fig.…”

Section: B Ion-photon Interactionmentioning

confidence: 99%

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Photoionization and fragmentation of H3O+under XUV irradiation

et al. 2013

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The photolysis of the hydronium cation H 3 O + has been studied at the extreme ultraviolet wavelengths of 35.56 ± 0.24 nm (34.87 ± 0.24 eV) and 21.85 ± 0.17 nm (56.74 ± 0.44 eV) using a crossed ion-photon beam setup at the free-electron laser FLASH. Coincidence photoelectron and photofragment spectroscopy was performed at 21.85 nm, where both inner and outer valence ionization are allowed, and revealed that the XUV photolysis of H 3 O + is by far dominated by ionization of outer valence electrons forming the 1 A 1 and 2 E states of the dication H 3 O 2+ . The dications were found to dissociate into the channels H 2 O + + H + (72 ± 4%), OH 0 + 2H + (18 ± 6%), and OH + + H + + H 0 (10 ± 1%). A kinematic analysis of the H 2 O + + H + channel after photoabsorption at 35.56 nm (where only outer valence ionization is possible) showed dissociation into excited states of the water radical ion, where the 1 A 1 state breaks up into the linearÃ 2 A 1 state of H 2 O + and the 2 E state decays into the strongly bentB 2 B 2 state. Finally, from the 2 E state of H 3 O 2+ , dissociation into OH 0 (X 2 ) + 2H + was identified to occur with a near linear dissociation geometry.

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“…In addition, triple detachment was measured. We also note that single and double detachment of O − was investigated recently with a free electron laser at a fixed photon energy [15]. So far, no experimental results on K-shell detachment were published for anions heavier than O − .…”

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confidence: 99%

Prominent role of multielectron processes inK-shell double and triple photodetachment of oxygen anions

et al. 2016

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The photon-ion merged-beams technique was used at a synchrotron light source for measuring absolute cross sections of double and triple photodetachment of O − ions. The experimental photon energy range of 524-543 eV comprised the threshold for K-shell ionization. Using resolving powers of up to 13000, the position, strength and width of the below-threshold 1s 2s 2 2p 6 2 S resonance as well as the positions of the 1s 2s 2 2p 5 3 P and 1s 2s 2 2p 5 1 P thresholds for K-shell ionization were determined with high-precision. In addition, systematically enlarged multi-configuration Dirac-Fock calculations have been performed for the resonant detachment cross sections. Results from these abinitio computations agree very well with the measurements for the widths and branching fractions for double and triple detachment, if double shake-up (and -down) of the valence electrons and the rearrangement of the electron density is taken into account. For the absolute cross sections, however, a previously found discrepancy between measurements and theory is confirmed. Negative atomic ions play an important role in lowtemperature plasmas such as the upper atmosphere or the interstellar medium [1] and also in technical applications. For example, in the context of antihydrogen production, it has been proposed to use an ensemble of laser-cooled anions as a coolant for antiprotons [2]. Negative ions are fundamentally different from neutral atoms or positive ions since the extra electron in a negative ion is not only bound by the long-range Coulomb interaction with the atomic nucleus but, more importantly, also by a short-range attractive force due to the polarization of the atomic core. The accurate theoretical description of these ions still challenges the state-of-the-art quantum computations although the numbers of their bound states are generally finite. The low-excitation levels of negative ions are readily accessible by laser spectroscopy (see, e.g., [3][4][5][6]). Therefore, this technique has been a prime source of experimental information about the mutual interactions among the valence electrons.A sensitive tool for studying the interactions between the valence and the core electrons is inner-shell ionization of negative ions [7,8]. Here, we apply the photon-ion merged-beams technique (see [9] for a recent overview) to determine the absolute cross sections for double and triple ionization (detachment) of oxygen anions in the photon energy range 524-543 eV. In this energy range, a K-shell vacancy may be produced either by direct ionization of an initial 1s electron or via the formation of a resonance state by exciting one 1s electron to a higher shell such as 2p. In either case, the K-vacancy decays subsequently by a cascade of radiative and nonradiative processes leading to a distribution of final charge states with O + and O 2+ as the most prominent charged reaction products. To test and better understand the theoretical prediction of such cascades, we performed extremely comprehensive quantum calculations for the formation...

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Single and double electron photodetachment from the oxygen anion at 41.7 nm

Cited by 7 publications

References 30 publications

Lifetime of low vibrational levels of the metastableB̃2B2state ofH2O+<

Lifetime of low vibrational levels of the metastableB̃2B2state ofH2O+<

Photoionization and fragmentation of H3O+under XUV irradiation

Prominent role of multielectron processes inK-shell double and triple photodetachment of oxygen anions

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