Simulation of x-ray absorption near-edge spectra and x-ray fluorescence spectra of optically excited molecules

Pandey, Rakesh Kumar; Mukamel, Shaul

doi:10.1063/1.2173243

Cited by 16 publications

(13 citation statements)

References 26 publications

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“…Transient occupation of these states is shown on the right-hand side panels of figure 3. We note that computational treatment of AS-RXRS from different excited molecules have been done before by Tanaka et al and Pandey et al [32,33].…”

Section: Resultsmentioning

confidence: 79%

Anti-Stokes resonant x-ray Raman scattering for atom specific and excited state selective dynamics

et al. 2016

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Ultrafast electronic and structural dynamics of matter govern rate and selectivity of chemical reactions, as well as phase transitions and efficient switching in functional materials. Since x-rays determine electronic and structural properties with elemental, chemical, orbital and magnetic selectivity, short pulse x-ray sources have become central enablers of ultrafast science. Despite of these strengths, ultrafast x-rays have been poor at picking up excited state moieties from the unexcited ones. With time-resolved anti-Stokes resonant x-ray Raman scattering (AS-RXRS) performed at the LCLS, and ab initio theory we establish background free excited state selectivity in addition to the elemental, chemical, orbital and magnetic selectivity of x-rays. This unparalleled selectivity extracts low concentration excited state species along the pathway of photo induced ligand exchange of Fe(CO) 5 in ethanol. Conceptually a full theoretical treatment of all accessible insights to excited state dynamics with AS-RXRS with transform-limited x-ray pulses is given-which will be covered experimentally by upcoming transform-limited x-ray sources.With the rapid evolution of sub-picosecond and femtosecond x-ray sources and particularly with the emergence x-ray free-electron lasers, first steps to join the unique electronic structure information of x-ray spectroscopy with the ultrafast time scale of dynamics in matter have been taken [1][2][3][4][5][6][7][8]. Often though, time resolved x-ray spectroscopy at these dilute transient species with x-ray absorption, x-ray fluorescence or electron spectroscopy suffer often from the difficult separation between the overlapping spectral signatures of the dilute excited state species and the ground state. To reach improved chemical selectivity with x-ray lasers nonlinear and OPEN ACCESS RECEIVED

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Section: Resultsmentioning

confidence: 79%

Anti-Stokes resonant x-ray Raman scattering for atom specific and excited state selective dynamics

et al. 2016

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“…By the definition of the KS potential, dn s ðrtÞ is the same in both Eqs. [35] and [36]. We can then insert Eq.…”

Section: Linear Responsementioning

confidence: 99%

“…[39] into Eq. [36], equate that result with Eq. [35], and solve for a general relation for any dn s ðrtÞ.…”

Section: Linear Responsementioning

confidence: 99%

“…In inorganic chemistry, the optical response of many transition metal complexes [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] has been calculated, as have some X-ray absorption spectra. 36,37 In organic chemistry, heterocycles [38][39][40][41][42][43] have been examined among others, [44][45][46] including the response of thiouracil, 47 s-tetrazine, 48 and annulated porphyrins. 49 We also see TDDFT's use in studying various fullerenes.…”

Section: Introductionmentioning

confidence: 99%

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Excited States from Time‐Dependent Density Functional Theory

Elliott¹,

Furche²,

Burke³

2008

Reviews in Computational Chemistry

222

195

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Time-dependent density functional theory (TDDFT) is presently enjoying enormous popularity in quantum chemistry, as a useful tool for extracting electronic excited state energies. This article explains what TDDFT is, and how it differs from ground-state DFT. We show the basic formalism, and illustrate with simple examples. We discuss its implementation and possible sources of error. We discuss many of the major successes and challenges of the theory, including weak fields, strong fields, continuum states, double excitations, charge transfer, high harmonic generation, multiphoton ionization, electronic quantum control, van der Waals interactions, transport through single molecules, currents, quantum defects, and, elastic electron-atom scattering. ContentsVII. Beyond standard functionals 22 A. Double excitations 22 B. Polymers 23 C. Solids 23 D. Charge transfer 23 VIII. Other topics 23 A. Ground-state XC energy 23 B. Strong fields 24 C. Transport 25

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“…We also report the three lowest unoccupied Hartree-Fock states of the water monomer with a fully relaxed oxygen 1s core hole. The latter are antibonding states of 4a 1 , 2b 2 and 3b 2 symmetry, respectively, and correspond to the three lowest energy features of the XAS spectrum in the gas phase [28]. The similarity of condensed and gas phase orbitals suggests that the XAS features in ice and water should be attributed to molecular excitons strongly perturbed by the environment.…”

mentioning

confidence: 99%

X-Ray Absorption Signatures of the Molecular Environment in Water and Ice

2010

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The x-ray absorption spectra of water and ice are calculated with a many-body approach for electron-hole excitations. The experimental features, including the small effects of temperature change in the liquid, are quantitatively reproduced from molecular configurations generated by abinitio molecular dynamics. The spectral difference between the solid and the liquid is due to two major short range order effects. One, due to breaking of hydrogen bonds, enhances the pre-edge intensity in the liquid. The other, due to a non-bonded molecular fraction in the first coordination shell, affects the main spectral edge in the conversion of ice to water. This effect may not involve hydrogen bond breaking as shown by experiment in high-density amorphous ice.PACS numbers: 36.20. Ng, 71.15.Pd, 32.10.Dk, 78.20.Ci The nature of the hydrogen bond (H-bond) network in water continues to be at the center of scientific debate [1]. A few years ago high-resolution x-ray absorption spectra (XAS) probed the local order of liquid and crystalline water phases, including the effect of temperature in the liquid [2]. These experiments stirred a storm of controversy because of their interpretation suggesting that a large fraction (>80%) of H-bonds are broken in the liquid [2]. This would imply an environment consisting primarily of chains and rings of H-bonds, in stark contrast with the conventional near-tetrahedral picture supported by diffraction [3] and other thermodynamic and spectroscopic data [4,5]. The broken H-bond fraction was estimated from the intensity of the pre-edge, which is prominent in the liquid and was believed to be absent in bulk ice. Subsequent x-ray Raman spectra, however, showed that the pre-edge feature is present, albeit with different intensity, not only in the liquid, but also in hexagonal (Ih), cubic (Ic), low-density amorphous (LDA) and highdensity amorphous (HDA) ice [6]. This experiment reported another interesting observation, namely that water and HDA ice have spectra with the main-edge more prominent than the post-edge, while the opposite behavior occurs in Ih, Ic, and LDA ice. This is puzzling given that both LDA and HDA ice are disordered structures with an insignificant fraction of broken H-bonds. Spectral calculations, based on electronic density-functional theory (DFT) and near-tetrahedral liquid models, correctly predicted the presence of three spectral features in ice and water and associated the enhancement of the pre-edge intensity to broken H-bonds [7,8,9,10]. However, the agreement with experiment was only semiquantitative and the calculations did not identify the cause of the significant changes in main-and post-edge spectra. These effects were generically attributed to disorder [8], but this does not explain why LDA and HDA ice show opposite behavior [6]. Finally, no attempt was made to discuss the effect of temperature in the liquid spectra, for which contrasting experimental data have been reported [2,11,12,13].In this paper we use liquid structures generated by ab-initio MD to compute x-ra...

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Simulation of x-ray absorption near-edge spectra and x-ray fluorescence spectra of optically excited molecules

Cited by 16 publications

References 26 publications

Anti-Stokes resonant x-ray Raman scattering for atom specific and excited state selective dynamics

Anti-Stokes resonant x-ray Raman scattering for atom specific and excited state selective dynamics

Excited States from Time‐Dependent Density Functional Theory

X-Ray Absorption Signatures of the Molecular Environment in Water and Ice

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