Soft X-ray microscopy and spectroscopy at the molecular environmental science beamline at the Advanced Light Source

Bluhm, Hendrik; Andersson, Klas; Araki, Tohru; Benzerara, Karim; Brown, Gordon E.; Dynes, J. J.; Ghosal, Sandip; Gilles, Mary K.; Hansen, Herbert; Hemminger, J. C.; Hitchcock, Adam P.; Ketteler, Guido; Kilcoyne, A. L. D.; Kneedler, E.; Lawrence, John R.; Leppard, Gary G.; Majzlam, J.; Mun, Bongjin Simon; Myneni, Satish Chandra Babu; Nilsson, Anders; Ogasawara, Hirohito; Ogletree, D. Frank; Pecher, Klaus; Salmerón, Miquel; Shuh, David K.; Tonner, B. P.; Tyliszczak, Tolek; Warwick, Tony; Yoon, Tae Hyun

doi:10.1016/j.elspec.2005.07.005

Cited by 298 publications

(241 citation statements)

References 65 publications

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“…As noted previously, 21 accurate comparisons between pre-edge intensities can be derived from both NIXS and transmission data because contributions from self-absorption and saturation effects are not present (NIXS) [30][31][32] or can be minimized/eliminated (STXM). 33 In contrast, FY measurements provide reduced spectral intensities due to saturation and/or self-absorption effects, stemming from the relative size of the particles compared to characteristic X-ray penetration lengths (~ 1 µm) and high concentrations of analyte required for the measurement. Hence, comparisons between NIXS and STXM data for MO 4 2-and MO 4 1-show that pre-edge peak positions decrease in energy from Group 6 to Group 7 (Mn < Cr, Tc < Mo, and Re < W), which is accompanied by an increase in pre-edge peak intensities measured for the Group 7 (MO 4 1-) compounds relative to Group 6 (MO 4 2-).…”

Section: Resultsmentioning

confidence: 99%

Covalency in Metal–Oxygen Multiple Bonds Evaluated Using Oxygen K-edge Spectroscopy and Electronic Structure Theory

et al. 2013

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X-ray absorption spectroscopy using fluorescence and transmission (via a scanning transmission X-ray microscope), and linear-response density functional theory. The results suggest that moving from Group 6 to Group 7 or down the triads increases M-O e* (π*) mixing. Meanwhile, t 2 * mixing (σ* + π*) remains relatively constant within the same Group. These unexpected changes in frontier orbital energy and composition are evaluated in terms of periodic trends in d orbital energy and radial extension. 3Introduction.The nature of chemical bonds between metals and light atoms such as oxygen, nitrogen, and carbon is of widespread interest because these interactions control the physics and chemistry of many technologically important processes and compounds. Light atoms are prone to form highly covalent metalligand multiple bonds involving one σ bond and one or more π bonds, resulting in oxo, imido, nitrido, alkylidene, alkylidyne, and carbido functionalities with many desirable chemical reactivities and physical properties. 1 Among this diverse group, metal oxides stand out because of their widespread presence in biological and bio-inspired processes and for applications utilizing their unique magnetic, electronic, and thermal properties. [2][3][4][5][6][7][8][9][10][11][12][13] Developing a clear understanding of how M-O electronic structure and orbital mixing changes for a range of metal oxo compounds and materials will greatly benefit attempts to advance these technologies.Among approaches explored previously, ligand K-edge X-ray absorption spectroscopy (XAS) has emerged as an effective method for quantitatively probing electronic structure and orbital mixing in metal-chlorine and metal-sulfur bonds. 14 This spectroscopic technique probes bound state transitions between core ligand 1s orbitals and unoccupied molecular orbitals. The excitations can only have transition intensity if the empty acceptor orbitals contain ligand p character. 14 At first glance, such an approach seems well-suited for studying metal-oxygen bonding. However, attempts to use this technique to study non-conducting molecular systems are complicated by experimental barriers derived from the low energy of the oxygen K-edge (ca. 530 eV), which magnifies issues associated with surface contamination, saturation, and self-absorption effects.In this manuscript, we overcome these challenges and evaluate relative changes in metal-oxo electronic structure and orbital mixing for non-conducting molecular solids using O K-edge spectroscopy in conjunction with hybrid density functional theory (DFT) calculations. Specifically, non-resonant inelastic X-ray scattering (NIXS), XAS, and linear-response density functional theory (TDDFT) are used as Density functional theory calculations using relativistic effective core potentials (RECPs) were conducted to determine how antibonding molecular orbital compositions and energies varied as (1) metals 5 changed within a group (Cr, Mo, W and Mn, Tc, Re) and (2) metal charges increased from M 6+ (Group 6) to M 7+ (Group 7)...

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Section: Resultsmentioning

confidence: 99%

Covalency in Metal–Oxygen Multiple Bonds Evaluated Using Oxygen K-edge Spectroscopy and Electronic Structure Theory

et al. 2013

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“…Liquid-jet experiments were performed at the Molecular Environmental Sciences beamline (11.0.2) at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory (LBNL) (48)(49)(50)(51)(52). The details of the experimental setup and procedures have been described previously (21).…”

Section: Methodsmentioning

confidence: 99%

Specific cation effects at aqueous solution−vapor interfaces: Surfactant-like behavior of Li ⁺ revealed by experiments and simulations

Perrine

Parry

Stern

et al. 2017

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

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It is now well established by numerous experimental and computational studies that the adsorption propensities of inorganic anions conform to the Hofmeister series. The adsorption propensities of inorganic cations, such as the alkali metal cations, have received relatively little attention. Here we use a combination of liquid-jet X-ray photoelectron experiments and molecular dynamics simulations to investigate the behavior of K + and Li + ions near the interfaces of their aqueous solutions with halide ions. Both the experiments and the simulations show that Li + adsorbs to the aqueous solution−vapor interface, while K + does not. Thus, we provide experimental validation of the "surfactant-like" behavior of Li + predicted by previous simulation studies. Furthermore, we use our simulations to trace the difference in the adsorption of K + and Li + ions to a difference in the resilience of their hydration shells.ion adsorption | air−water interface | specific ion effects | Hofmeister series | aqueous ionic solvation M yriad chemical and biochemical processes that occur in aqueous salt solutions exhibit trends that depend systematically on the identities of the salt ions. These trends, which are commonly referred to as specific ion effects, generally follow the Hofmeister series, a ranking of the ability of salt ions to precipitate proteins that was developed by Franz Hofmeister (1) in the late 1800s. The Hofmeister series applies, however, to a wide range of other seemingly unrelated phenomena, such as colloidal stability, critical micelle concentrations, chromatographic selectivity, protein denaturation temperatures, and the interfacial properties of aqueous salt solutions (2, 3). Early attempts to explain the Hofmeister series relied on the notion that salt ions have a long-range effect on the structure of water, with ions on one side of the series acting as "structure makers" and ions on the other side as "structure breakers" (2, 4). However, more recently, several experimental and computational studies have questioned the role of long-range ordering/disordering effects (4-9), and have provided compelling evidence that ion-specific behavior at aqueous interfaces must be taken into consideration when attempting to explain Hofmeister effects (7, 10-13).Specific anion effects on the interfacial properties of aqueous salt solutions, such as surface tensions and surface potentials, closely follow the Hofmeister series for anions (14). For example, surface tension increments (STIs; differences between the surface tension of a salt solution and that of neat water) of sodium salts at the same concentration decrease in the order: SO 4 2− > Cl − > Br − > NO 3 − > I − (15, 16). Molecular dynamics (MD) simulations have predicted that the propensity of anions to adsorb to the solution-vapor interface follows the Hofmeister series in reverse (7,14,17), and this prediction has largely been confirmed experimentally (14,(18)(19)(20)(21)(22). Moreover, MD simulations have shown that, with few exceptions [e.g., SO 4 2− in (NH 4 ) 2...

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“…At both facilities, the beamlines operated with a 0.5 atm He-filled chamber and used elliptically polarizing undulators that delivered photons to entrance slit-less plane-grating monochromators. [137][138][139][140] This provides a 130 to 2700 eV working energy range at the CLS, and a 90 to 1950 eV working energy range at the ALS. Energy calibrations were performed at the Ne K-edge for Ne (867.3 eV).…”

Section: Methodsmentioning

confidence: 99%

A Macrocyclic Chelator That Selectively Binds Ln⁴⁺ over Ln³⁺ by a Factor of 10²⁹

et al. 2016

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Abstract.A tetravalent cerium macrocyclic complex (CeLK4) was prepared with an octadentate terephthalamide ligand comprised of hard catecholate donors, and characterized in the solution state by spectrophotometric titrations and electrochemistry, and in the crystal by X-ray diffraction. The solution state studies showed that L exhibits a remarkably high affinity towards Ce 4+ , with log β110 = 61(2) and ΔG = -348 kJ/mol, compared with log β110 = 32.02(2) for the analogous Pr 3+ complex. In addition, L exhibits an unusual preference for forming CeL 4-relative to formation of the analogous actinide complex, ThL 4-, which has β110 = 53.7(5). The extreme stabilization of tetravalent cerium relative to its trivalent state is also evidenced by the shift of 1.91 V in redox potential of the Ce 3+ /Ce 4+ couple of the complex (measured at -0.454 V vs. SHE). The unprecedented behavior prompted an electronic structure analysis using L3 and M5,4-edge X-ray absorption near-edge structure (XANES) spectroscopies and configuration interaction calculations, which showed that 4f orbital bonding in CeLK4 has partial covalent character owing to ligand-to-metal charge transfer (LMCT) in the ground state. The experimental results are presented in the context of earlier measurements on tetravalent cerium compounds, indicating that the amount LMCT for CeLK4 is similar to that observed for [Et4N]2[CeCl6] and CeO2, and significantly less than that for the organometallic sandwich compound cerocene, (C8H8)2Ce. A simple model to rationalize changes in 4f orbitals for tri-and tetravalent lanthanide and actinide compounds is also provided.

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Soft X-ray microscopy and spectroscopy at the molecular environmental science beamline at the Advanced Light Source

Cited by 298 publications

References 65 publications

Covalency in Metal–Oxygen Multiple Bonds Evaluated Using Oxygen K-edge Spectroscopy and Electronic Structure Theory

Covalency in Metal–Oxygen Multiple Bonds Evaluated Using Oxygen K-edge Spectroscopy and Electronic Structure Theory

Specific cation effects at aqueous solution−vapor interfaces: Surfactant-like behavior of Li ⁺ revealed by experiments and simulations

A Macrocyclic Chelator That Selectively Binds Ln⁴⁺ over Ln³⁺ by a Factor of 10²⁹

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Soft X-ray microscopy and spectroscopy at the molecular environmental science beamline at the Advanced Light Source

Cited by 298 publications

References 65 publications

Covalency in Metal–Oxygen Multiple Bonds Evaluated Using Oxygen K-edge Spectroscopy and Electronic Structure Theory

Covalency in Metal–Oxygen Multiple Bonds Evaluated Using Oxygen K-edge Spectroscopy and Electronic Structure Theory

Specific cation effects at aqueous solution−vapor interfaces: Surfactant-like behavior of Li + revealed by experiments and simulations

A Macrocyclic Chelator That Selectively Binds Ln4+ over Ln3+ by a Factor of 1029

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Specific cation effects at aqueous solution−vapor interfaces: Surfactant-like behavior of Li ⁺ revealed by experiments and simulations

A Macrocyclic Chelator That Selectively Binds Ln⁴⁺ over Ln³⁺ by a Factor of 10²⁹