Time-resolved soft X-ray absorption spectroscopy in transmission mode on liquids at MHz repetition rates

Fondell, Mattis; Eckert, Sebastian; Jay, Raphael M.; Weniger, Christian; Quevedo, Wilson; Niskanen, Johannes; Kennedy, Brian; Sorgenfrei, F.; Schick, Daniel; Giangrisostomi, Erika; Ovsyannikov, Ruslan; Adamczyk, Katrin; Huse, Nils; Wernet, Philippe; Mitzner, R.; Föhlisch, Alexander

doi:10.1063/1.4993755

Cited by 58 publications

(60 citation statements)

References 55 publications

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“…3 ), which goes hand in hand with a transfer of charge. The oscillations of the spectral shifts can be associated with changes of the partial charges in the vicinity of the absorbing atoms, 57,58 which are linked to oscillations in the bond lengths.…”

Section: Resultsmentioning

confidence: 99%

Simulation of time-resolved x-ray absorption spectroscopy of ultrafast dynamics in particle-hole-excited 4‐(2-thienyl)-2,1,3-benzothiadiazole

Khalili

Inhester

Arnold

et al. 2020

Structural Dynamics

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To date, alternating co-polymers based on electron-rich and electron-poor units are the most attractive materials to control functionality of organic semiconductor layers in which ultrafast excited-state processes play a key role. We present a computational study of the photoinduced excited-state dynamics of the 4-(2-thienyl)-2,1,3-benzothiadiazole (BT-1T) molecule, which is a common building block in the backbone of π -conjugated polymers used for organic electronics. In contrast to homo-polymer materials, such as oligothiophene, BT-1T has two non-identical units, namely, thiophene and benzothiadiazole, making it attractive for intramolecular charge transfer studies. To gain a thorough understanding of the coupling of excited-state dynamics with nuclear motion, we consider a scenario based on femtosecond time-resolved x-ray absorption spectroscopy using an x-ray free-electron laser in combination with a synchronized ultraviolet femtosecond laser. Using Tully's fewest switches surface hopping approach in combination with excited-state calculations at the level of configuration interaction singles, we calculate the gas-phase x-ray absorption spectrum at the carbon and nitrogen K edges as a function of time after excitation to the lowest electronically excited state. The results of our time-resolved calculations exhibit the charge transfer driven by non-Born-Oppenheimer physics from the benzothiadiazole to thiophene units during relaxation to the ground state. Furthermore, our ab initio molecular dynamics simulations indicate that the excited-state relaxation processes involve bond elongation in the benzothiadiazole unit as well as thiophene ring puckering at a time scale of 100 fs. We show that these dynamical trends can be identified from the time-dependent x-ray absorption spectrum.

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Section: Resultsmentioning

confidence: 99%

Simulation of time-resolved x-ray absorption spectroscopy of ultrafast dynamics in particle-hole-excited 4‐(2-thienyl)-2,1,3-benzothiadiazole

Khalili

Inhester

Arnold

et al. 2020

Structural Dynamics

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“…The figure illustrates that the Cr L-edge around 580 eV is very close to the near-edge absorption resonances of the O K-edge at 540 eV merging at higher energies with the O K-edge extended X-ray absorption fine structure (EXAFS) at 580 eV and beyond. 44–46 Therefore, even more than for Mn L-edge XAS 14 or Fe L-edge XAS 24 careful treatment of the absorption background due to the solvent and its changes due to possible instabilities of the flatjet thickness is necessary for Cr L-edge XAS (see the Materials and Methods section and Figures S2–S4 in the Supporting Information for a more detailed discussion of this aspect).…”

Section: Resultsmentioning

confidence: 99%

“…Here, we use a fast-flowing liquid flat-jet system 14,23,24 to measure the Cr L-edge transmission XAS spectrum of Cr III (acac) 3 in solution free of X-ray-induced sample damage. Cr III (acac) 3 has formally three Cr 3d electrons and a near octahedral CrO 6 core as found from crystallographic 25,26 and UV–vis investigations, 27–29 see Figure 1A.…”

Section: Introductionmentioning

confidence: 99%

Cr L-Edge X-ray Absorption Spectroscopy of Cr^III(acac)₃ in Solution with Measured and Calculated Absolute Absorption Cross Sections

et al. 2018

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X-ray absorption spectroscopy at the L-edge of 3d transition metals is widely used for probing the valence electronic structure at the metal site via 2p-3d transitions. Assessing the information contained in L-edge absorption spectra requires systematic comparison of experiment and theory. We here investigate the Cr L-edge absorption spectrum of high-spin chromium acetylacetonate Cr(acac) in solution. Using a transmission flatjet enables determining absolute absorption cross sections and spectra free from X-ray-induced sample damage. We address the challenges of measuring Cr L absorption edges spectrally close to the O K absorption edge of the solvent. We critically assess how experimental absorption cross sections can be used to extract information on the electronic structure of the studied system by comparing our results of this Cr (3d) complex to our previous work on L-edge absorption cross sections of Mn(acac) (3d) and Mn(acac) (3d). Considering our experimental uncertainties, the most insightful experimental observable for this d(Cr)-d(Mn)-d(Mn) series is the L-edge branching ratio, and we discuss it in comparison to semiempirical multiplet theory and ab initio restricted active space calculations. We further discuss and analyze trends in integrated absorption cross sections and correlate the spectral shapes with the local electronic structure at the metal sites.

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“…The XAS of Fig. 3 was recorded by using the flat-jet transmission near-edge X-ray absorption fine structure setup ( 55 ) at BESSY-II. The ionization step of Fig.…”

Section: Methodsmentioning

confidence: 99%

Compatibility of quantitative X-ray spectroscopy with continuous distribution models of water at ambient conditions

Niskanen

Fondell

Sahle

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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The phase diagram of water harbors controversial views on underlying structural properties of its constituting molecular moieties, its fluctuating hydrogen-bonding network, as well as pair-correlation functions. In this work, long energy-range detection of the X-ray absorption allows us to unambiguously calibrate the spectra for water gas, liquid, and ice by the experimental atomic ionization cross-section. In liquid water, we extract the mean value of 1.74 ± 2.1% donated and accepted hydrogen bonds per molecule, pointing to a continuous-distribution model. In addition, resonant inelastic X-ray scattering with unprecedented energy resolution also supports continuous distribution of molecular neighborhoods within liquid water, as do X-ray emission spectra once the femtosecond scattering duration and proton dynamics in resonant X-ray–matter interaction are taken into account. Thus, X-ray spectra of liquid water in ambient conditions can be understood without a two-structure model, whereas the occurrence of nanoscale-length correlations within the continuous distribution remains open.

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Time-resolved soft X-ray absorption spectroscopy in transmission mode on liquids at MHz repetition rates

Cited by 58 publications

References 55 publications

Simulation of time-resolved x-ray absorption spectroscopy of ultrafast dynamics in particle-hole-excited 4‐(2-thienyl)-2,1,3-benzothiadiazole

Simulation of time-resolved x-ray absorption spectroscopy of ultrafast dynamics in particle-hole-excited 4‐(2-thienyl)-2,1,3-benzothiadiazole

Cr L-Edge X-ray Absorption Spectroscopy of Cr^III(acac)₃ in Solution with Measured and Calculated Absolute Absorption Cross Sections

Compatibility of quantitative X-ray spectroscopy with continuous distribution models of water at ambient conditions

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Time-resolved soft X-ray absorption spectroscopy in transmission mode on liquids at MHz repetition rates

Cited by 58 publications

References 55 publications

Simulation of time-resolved x-ray absorption spectroscopy of ultrafast dynamics in particle-hole-excited 4‐(2-thienyl)-2,1,3-benzothiadiazole

Simulation of time-resolved x-ray absorption spectroscopy of ultrafast dynamics in particle-hole-excited 4‐(2-thienyl)-2,1,3-benzothiadiazole

Cr L-Edge X-ray Absorption Spectroscopy of CrIII(acac)3 in Solution with Measured and Calculated Absolute Absorption Cross Sections

Compatibility of quantitative X-ray spectroscopy with continuous distribution models of water at ambient conditions

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Cr L-Edge X-ray Absorption Spectroscopy of Cr^III(acac)₃ in Solution with Measured and Calculated Absolute Absorption Cross Sections