Threshold Photodetachment in a Repulsive Potential

Lindahl, Anton; Rohlén, J.; Hultgren, H.; Kiyan, Igor Yu.; Pegg, D. J.; Walter, C. W.; Hanstorp, Dag

doi:10.1103/physrevlett.108.033004

Cited by 11 publications

(32 citation statements)

References 22 publications

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“…The values for the resonance energies and widths extracted from these fits are also given in Table I. Resonance E has previously been investigated in the K(7 2 S) and K(5 2 G) channels [17]; these parameters are also presented in Table I. The values of the resonance parameters differ slightly between the previous and present study.…”

Section: Resultsmentioning

confidence: 60%

“…However, it is also possible for an excited atomic state to have a negative polarizability. This more unusual case was discussed in a recent publication [17] where the fundamentally different behaviors of the cross sections at the K(5 2 F ) and K(5 2 G) thresholds were described. These two states have dipole polarizabilities of approximately the same large magnitude (10 6 a.u.…”

Section: Introductionmentioning

confidence: 90%

“…The apparatus and the experimental procedure employed are described in detail. The same facility was used in the study of threshold behaviors of the cross sections at the K(5 2 F ) and K(5 2 G) thresholds [17] discussed above. In the present work, partial cross sections were measured for final-state channels leading to the formation of the residual K atom in the excited 7 2 S, 5 2 F , and 5 2 G states.…”

Section: Introductionmentioning

confidence: 99%

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Experimental studies of partial photodetachment cross sections in K−below the K(7 2P) threshold

et al. 2012

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A collinear beams apparatus has been used to determine photodetachment cross sections for K − in the photon energy range 4.250-4.360 eV. State-selective detection, utilizing a resonance ionization scheme, was applied to measure partial cross sections for those channels which leave the residual K atoms in the excited 7 2 S, 5 2 F , and 5 2 G states. The energy region studied encompassed the openings of the aforementioned channels, as well as the channel that leaves the K atom in the 7 2 P state. Two previously unobserved resonances were seen in all three partial cross sections between the K(5 2 G) and K(7 2 P ) thresholds. It is shown that a more reliable determination of resonance parameters can be made if the same resonances are observed in several channels. In the region below the K(5 2 F ) threshold, three previously observed resonances were investigated [Kiyan et al., Phys. Rev. Lett. 84, 5979 (2000)]. A greatly increased modulation of the signal was obtained by detecting in the K(7 2 S) channel instead of the K(5 2 S) channel used in the previous study. Furthermore, the shapes of the cross sections in the threshold regions are discussed. A detailed description of the apparatus and the experimental procedure employed is presented in the paper.

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Section: Resultsmentioning

confidence: 60%

Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

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Experimental studies of partial photodetachment cross sections in K−below the K(7 2P) threshold

et al. 2012

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“…Even for the single negative atomic ion, Fe − , it is a nontrivial task for both experimental and theoretical investigation678910111213141516. The properties of negative ions differ significantly from both positive ions and neutral systems17181920. Like the ionization potential, the electron affinity (EA) is a fundamental parameter for understanding chemical properties of elements2122.…”

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Accurate Electron Affinity of Iron and Fine Structures of Negative Iron ions

Chen

Luo

et al. 2016

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Ionization potential (IP) is defined as the amount of energy required to remove the most loosely bound electron of an atom, while electron affinity (EA) is defined as the amount of energy released when an electron is attached to a neutral atom. Both IP and EA are critical for understanding chemical properties of an element. In contrast to accurate IPs and structures of neutral atoms, EAs and structures of negative ions are relatively unexplored, especially for the transition metal anions. Here, we report the accurate EA value of Fe and fine structures of Fe− using the slow electron velocity imaging method. These measurements yield a very accurate EA value of Fe, 1235.93(28) cm−1 or 153.236(34) meV. The fine structures of Fe− were also successfully resolved. The present work provides a reliable benchmark for theoretical calculations, and also paves the way for improving the EA measurements of other transition metal atoms to the sub cm−1 accuracy.

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“…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.…”

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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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Threshold Photodetachment in a Repulsive Potential

Cited by 11 publications

References 22 publications

Experimental studies of partial photodetachment cross sections in K−below the K(7 2P) threshold

Experimental studies of partial photodetachment cross sections in K−below the K(7 2P) threshold

Accurate Electron Affinity of Iron and Fine Structures of Negative Iron ions

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

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