Search

Your search keyword '"Electronic structure of atoms and molecules"' showing total 5 results
Start Over Descriptor "Electronic structure of atoms and molecules" Publisher springer nature
5 results on '"Electronic structure of atoms and molecules"'

1. Measurement of coherent vibrational dynamics with X-ray Transient Absorption Spectroscopy simultaneously at the Carbon K- and Chlorine L 2,3 - edges.

Author

Ross AD, Hait D, Scutelnic V, Neumark DM, Head-Gordon M, and Leone SR

Abstract

X-ray Transient Absorption Spectroscopy (XTAS) is a powerful probe for ultrafast molecular dynamics. The evolution of XTAS signal is controlled by the shapes of potential energy surfaces of the associated core-excited states, which are difficult to directly measure. Here, we study the vibrational dynamics of Raman activated CCl 4 with XTAS targeting the C 1s and Cl 2p electrons. The totally symmetric stretching mode leads to concerted elongation or contraction in bond lengths, which in turn induce an experimentally measurable red or blue shift in the X-ray absorption energies associated with inner-shell electron excitations to the valence antibonding levels. The ratios between slopes of different core-excited potential energy surfaces (CEPESs) thereby extracted agree very well with Restricted Open-Shell Kohn-Sham calculations. The other, asymmetric, modes do not measurably contribute to the XTAS signal. The results highlight the ability of XTAS to reveal coherent nuclear dynamics involving  < 0.01 Å atomic displacements and also provide direct measurement of forces on CEPESs., Competing Interests: Competing interestsThe authors declare the following competing interest: M.H.G. is a part-owner of Q.-Chem, which is the software platform in which the quantum chemical calculations were carried out. All other authors declare no competing interests., (© The Author(s) 2024.)

Published
2024
Full Text
View/download PDF

2. Laser excitation of the 1 S -2 S transition in singly-ionized helium.

Author

Gründeman EL, Barbé V, Martínez de Velasco A, Roth C, Collombon M, Krauth JJ, Dreissen LS, Taïeb R, and Eikema KSE

Abstract

Laser spectroscopy of atomic hydrogen and hydrogen-like atoms is a powerful tool for tests of fundamental physics. The 1 S -2 S transition of hydrogen in particular is a cornerstone for stringent Quantum Electrodynamics (QED) tests and for an accurate determination of the Rydberg constant. We report laser excitation of the 1 S -2 S transition in singly-ionized helium ( 3 He + ), a hydrogen-like ion with much higher sensitivity to QED than hydrogen itself. The transition requires two-photon excitation in the challenging extreme ultraviolet wavelength range, which we achieve with a tabletop coherent laser system suitable for precision spectroscopy. The transition is excited by combining an ultrafast amplified pulse at 790 nm (derived from a frequency comb laser) with its 25th harmonic at 32 nm (produced by high-harmonic generation). The results are well described by our simulations and we achieve a sizable 2S excitation fraction of 10 -4 per pulse, paving the way for future precision studies., Competing Interests: Competing interestsThe authors declare no competing interests., (© The Author(s) 2024.)

Published
2024
Full Text
View/download PDF

3. Parametrization of energy sharing distributions in direct double photoionization of He

Author

O. Talaee, M. Wallner, Jan M. Rost, Raj Singh, Vitali Zhaunerchyk, Dimitris Koulentianos, J. H. D. Eland, Sergey Zagorodskikh, J. Andersson, A. Hult Roos, Raimund Feifel, and Richard J. Squibb

Subjects
Physics, Multidisciplinary, Double ionization, Atom and Molecular Physics and Optics, 010401 analytical chemistry, lcsh:R, lcsh:Medicine, Atomic and molecular interactions with photons, Ranging, Photoionization, Electron, 01 natural sciences, Article, 0104 chemical sciences, Computational physics, Distribution (mathematics), Simple (abstract algebra), 0103 physical sciences, lcsh:Q, Atom- och molekylfysik och optik, Electronic structure of atoms and molecules, 010306 general physics, Wave function collapse, lcsh:Science, Parametrization
Abstract

We present experimental results on the characteristic sharing of available excess energy, ranging from 11–221 eV, between two electrons in single-photon direct double ionization of He. An effective parametrization of the sharing distributions is presented along with an empirical model that describes the complete shape of the distribution based on a single experimentally determinable parameter. The measured total energy sharing distributions are separated into two distributions representing the shake-off and knock-out parts by simulating the sharing distribution curves expected from a pure wave collapse after a sudden removal of the primary electron. In this way, empirical knock-out distributions are extracted and both the shake-off and knock-out distributions are parametrized. These results suggest a simple method that can be applied to other atomic and molecular systems to experimentally study important aspects of the direct double ionization process.

Published
2019

4. Disentangling Auger decays in O₂ by photoelectron-ion coincidences

Author

Liu, X.-J. (Xiao-Jing), Nicolas, C. (Christophe), Patanen, M. (Minna), and Miron, C. (Catalin)

Subjects
Chemical physics, Physics::Atomic and Molecular Clusters, Physics::Atomic Physics, Electronic structure of atoms and molecules, Characterization and analytical techniques
Abstract

In non-resonant Auger electron spectroscopies, multi core-ionized states lead to numerous energetically close-lying electronic transitions in Auger spectra, this hampering the assignment and interpretation of the experimental results. Here we reveal a new method to overcome this intrinsic limitation of non-resonant inner-shell spectroscopies. In a proof-of-principle experiment performed for the O₂ molecule, most of the Auger final states are dissociative, and we measure in coincidence the kinetic energy of the photoelectron and the kinetic energy release of the (O⁺, O⁺) ion pairs produced after the Auger decay of the O 1s−1 core-ionized states. The Auger final states are assigned using energy conservation. We fully separate the contributions from the ⁴Σ− and ²Σ− intermediate ionic states and conclusively demonstrate that the Auger decay probability can dramatically depend on the different O₂ 1s−1 intermediate multiplet states. In addition, a metastable Auger final state also exists, with lifetime longer than 3.8 μs, and clear changes are observed in both branching ratio and spectral profile of the O 1s photoelectron spectrum when they are recorded in coincidence with either O₂⁺⁺ or with other ionic species. These changes are attributed to the population of the metastable B′³Σ−u(ν′′=0) Auger final state via different intermediate states.

Published
2017

5. Relation between molecular electronic structure and nuclear spin-induced circular dichroism

Author

Štěpánek, P. (Petr), Coriani, S. (Sonia), Sundholm, D. (Dage), Ovchinnikov, V. A. (Vasily A.), Vaara, J. (Juha), Štěpánek, P. (Petr), Coriani, S. (Sonia), Sundholm, D. (Dage), Ovchinnikov, V. A. (Vasily A.), and Vaara, J. (Juha)

Abstract

The recently theoretically described nuclear spin-induced circular dichroism (NSCD) is a promising method for the optical detection of nuclear magnetization. NSCD involves both optical excitations of the molecule and hyperfine interactions and, thus, it offers a means to realize a spectroscopy with spatially localized, high-resolution information. To survey the factors relating the molecular and electronic structure to the NSCD signal, we theoretically investigate NSCD of twenty structures of the four most common nucleic acid bases (adenine, guanine, thymine, cytosine). The NSCD signal correlates with the spatial distribution of the excited states and couplings between them, reflecting changes in molecular structure and conformation. This constitutes a marked difference to the nuclear magnetic resonance (NMR) chemical shift, which only reflects the local molecular structure in the ground electronic state. The calculated NSCD spectra are rationalized by means of changes in the electronic density and by a sum-over-states approach, which allows to identify the contributions of the individual excited states. Two separate contributions to NSCD are identified and their physical origins and relative magnitudes are discussed. The results underline NSCD spectroscopy as a plausible tool with a power for the identification of not only different molecules, but their specific structures as well.

Published
2017

Catalog

Books, media, physical & digital resources
See catalog results