scholarly journals X-ray emission spectroscopy: a genetic algorithm to disentangle core–hole-induced dynamics

2021 ◽  
Vol 140 (12) ◽  
Author(s):  
Lars G. M. Pettersson ◽  
Osamu Takahashi
Keyword(s):  
Genetic Algorithm ◽  
Cross Sections ◽  
Potential Energy Surfaces ◽  
Water Clusters ◽  
Life Time ◽  
Core Hole ◽  
Final State ◽  
X Ray ◽  
State Potential ◽  
Energy Surfaces

AbstractA genetic algorithm (GA) is developed and applied to make proper connections of final-state potential-energy surfaces and X-ray emission (XES) cross sections between steps in the time-propagation of H-bonded systems after a core–hole is created. We show that this modification results in significantly improved resolution of spectral features in XES with the semiclassical Kramers–Heisenberg approach which takes into account important interference effects. We demonstrate the effects on a water pentamer model as well as on two 17-molecules water clusters representing, respectively, tetrahedral (D2A2) and asymmetric (D1A1) H-bonding environments. For D2A2, the applied procedure improves significantly the obtained intensities, whereas for D1A1 the effects are smaller due to milder dynamics during the core–hole life-time as only one hydrogen is involved. We reinvestigate XES for liquid ethanol and, by properly disentangling the relevant states in the dense manifold of states using the GA, now resolve the important 3a′′ state as a peak rather than a shoulder. Furthermore, by applying the SpecSwap-RMC procedure, we reweigh the distribution of structures in the sampling of the liquid to fit to experiment and estimate the ratio between the main anti and gauche conformers in the liquid at room temperature. This combination of techniques will be generally applicable to challenging problems in liquid-phase spectroscopy.

Observation of the geometric phase effect in the H + HD → H2+ D reaction

Science ◽  
2018 ◽  
Vol 362 (6420) ◽  
pp. 1289-1293 ◽  
Author(s):  
Daofu Yuan ◽  
Yafu Guan ◽  
Wentao Chen ◽  
Hailin Zhao ◽  
Shengrui Yu ◽  
...  
Keyword(s):  
Cross Sections ◽  
Geometric Phase ◽  
Potential Energy Surfaces ◽  
Molecular Beams ◽  
Conical Intersection ◽  
Molecular Systems ◽  
Quantum State Resolved ◽  
State Potential ◽  
Energy Surfaces ◽  
Angular Oscillations

Theory has established the importance of geometric phase (GP) effects in the adiabatic dynamics of molecular systems with a conical intersection connecting the ground- and excited-state potential energy surfaces, but direct observation of their manifestation in chemical reactions remains a major challenge. Here, we report a high-resolution crossed molecular beams study of the H + HD → H2+ D reaction at a collision energy slightly above the conical intersection. Velocity map ion imaging revealed fast angular oscillations in product quantum state–resolved differential cross sections in the forward scattering direction for H2products at specific rovibrational levels. The experimental results agree with adiabatic quantum dynamical calculations only when the GP effect is included.

scholarly journals Erratum: Ground state potential energy surfaces around selected atoms from resonant inelastic x-ray scattering

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Simon Schreck ◽  
Annette Pietzsch ◽  
Brian Kennedy ◽  
Conny Såthe ◽  
Piter S. Miedema ◽  
...  
Keyword(s):  
Potential Energy ◽  
Ground State ◽  
Potential Energy Surfaces ◽  
X Ray ◽  
X Ray Scattering ◽  
State Potential ◽  
Energy Surfaces ◽  
Ray Scattering

scholarly journals Ground state potential energy surfaces around selected atoms from resonant inelastic x-ray scattering

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Simon Schreck ◽  
Annette Pietzsch ◽  
Brian Kennedy ◽  
Conny Såthe ◽  
Piter S. Miedema ◽  
...  
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ground State ◽  
Potential Energy Surfaces ◽  
Energy Surface ◽  
X Ray ◽  
X Ray Scattering ◽  
State Potential ◽  
Energy Surfaces ◽  
Ray Scattering

Abstract Thermally driven chemistry as well as materials’ functionality are determined by the potential energy surface of a systems electronic ground state. This makes the potential energy surface a central and powerful concept in physics, chemistry and materials science. However, direct experimental access to the potential energy surface locally around atomic centers and to its long-range structure are lacking. Here we demonstrate how sub-natural linewidth resonant inelastic soft x-ray scattering at vibrational resolution is utilized to determine ground state potential energy surfaces locally and detect long-range changes of the potentials that are driven by local modifications. We show how the general concept is applicable not only to small isolated molecules such as O2 but also to strongly interacting systems such as the hydrogen bond network in liquid water. The weak perturbation to the potential energy surface through hydrogen bonding is observed as a trend towards softening of the ground state potential around the coordinating atom. The instrumental developments in high resolution resonant inelastic soft x-ray scattering are currently accelerating and will enable broad application of the presented approach. With this multidimensional potential energy surfaces that characterize collective phenomena such as (bio)molecular function or high-temperature superconductivity will become accessible in near future.

scholarly journals Solvent control of charge transfer excited state relaxation pathways in [Fe(2,2′-bipyridine)(CN)4]2−

2018 ◽  
Vol 20 (6) ◽  
pp. 4238-4249 ◽  
Author(s):  
Kasper S. Kjær ◽  
Kristjan Kunnus ◽  
Tobias C. B. Harlang ◽  
Tim B. Van Driel ◽  
Kathryn Ledbetter ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Optical Studies ◽  
X Ray ◽  
Solvent Influence ◽  
Solvent Control ◽  
State Potential ◽  
Energy Surfaces

By combining transient X-ray and optical studies, we reveal the solvent influence on excited state potential energy surfaces of [Fe(bpy)(CN)4]2−.

scholarly journals Finding intersections between electronic excited state potential energy surfaces with simultaneous ultrafast X-ray scattering and spectroscopy

2019 ◽  
Vol 10 (22) ◽  
pp. 5749-5760 ◽  
Author(s):  
Kasper S. Kjær ◽  
Tim B. Van Driel ◽  
Tobias C. B. Harlang ◽  
Kristjan Kunnus ◽  
Elisa Biasin ◽  
...  
Keyword(s):  
Excited State ◽  
Potential Energy ◽  
Free Electron ◽  
Free Electron Laser ◽  
Potential Energy Surfaces ◽  
X Ray ◽  
X Ray Scattering ◽  
State Potential ◽  
Laser Techniques ◽  
Energy Surfaces

Combined X-ray free-electron laser techniques pinpoints loci of intersections between potential energy surfaces of a photo-excited 3d transition-metal centered molecule.

Resolving the Quadruple Bonding Conundrum in C2 Using Insights Derived from Excited State Potential Energy Surfaces: A Molecular Orbital Perspective

2019 ◽  
Author(s):  
Ishita Bhattacharjee ◽  
Debashree Ghosh ◽  
Ankan Paul
Keyword(s):  
Excited State ◽  
Potential Energy ◽  
Molecular Orbital ◽  
High Spin ◽  
Potential Energy Surfaces ◽  
Valence Bond ◽  
Deep Minimum ◽  
State Potential ◽  
Energy Surfaces ◽  
Mo Theory

The question of quadruple bonding in C<sub>2</sub> has emerged as a hot button issue, with opinions sharply divided between the practitioners of Valence Bond (VB) and Molecular Orbital (MO) theory. Here, we have systematically studied the Potential Energy Curves (PECs) of low lying high spin sigma states of C<sub>2</sub>, N<sub>2</sub> and Be<sub>2</sub> and HC≡CH using several MO based techniques such as CASSCF, RASSCF and MRCI. The analyses of the PECs for the<sup> 2S+1</sup>Σ<sub>g/u</sub> (with 2S+1=1,3,5,7,9) states of C<sub>2</sub> and comparisons with those of relevant dimers and the respective wavefunctions were conducted. We contend that unlike in the case of N<sub>2</sub> and HC≡CH, the presence of a deep minimum in the <sup>7</sup>Σ state of C<sub>2</sub> and CN<sup>+</sup> suggest a latent quadruple bonding nature in these two dimers. Hence, we have struck a reconciliatory note between the MO and VB approaches. The evidence provided by us can be experimentally verified, thus providing the window so that the narrative can move beyond theoretical conjectures.

scholarly journals Ultraviolet spectroscopy of pressurized and supercritical carbon dioxide

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Timothy W. Marin ◽  
Ireneusz Janik
Keyword(s):  
Carbon Dioxide ◽  
Potential Energy Surfaces ◽  
Vacuum Ultraviolet ◽  
Electronic Absorption Spectra ◽  
Industrial Applications ◽  
Ultraviolet Spectroscopy ◽  
Collisional Broadening ◽  
Thermodynamic Critical Point ◽  
State Potential ◽  
Energy Surfaces

AbstractCarbon dioxide (CO2) is prevalent in planetary atmospheres and sees use in a variety of industrial applications. Despite its ubiquitous nature, its photochemistry remains poorly understood. In this work we explore the density dependence of pressurized and supercritical CO2 electronic absorption spectra by vacuum ultraviolet spectroscopy over the wavelength range 1455-2000 Å. We show that the lowest absorption band transition energy is unaffected by a density increase up to and beyond the thermodynamic critical point (137 bar, 308 K). However, the diffuse vibrational structure inherent to the spectrum gradually decreases in magnitude. This effect cannot be explained solely by collisional broadening and/or dimerization. We suggest that at high densities close proximity of neighboring CO2 molecules with a variety of orientations perturbs the multiple monomer electronic state potential energy surfaces, facilitating coupling between binding and dissociative states. We estimate a critical radius of ~4.1 Å necessary to cause such perturbations.

Sign in / Sign up

Export Citation Format

Share Document