Sökresultat

The interfacial reduction of aqueous [PdCl4]2- at the interface with an organic solution of ferrocene has been characterised by X-ray absorption fine structure (XAFS) spectroscopy. Use of a liquid-liquid interface as a model for homogeneous nucleation permits control of the thermodynamic driving force for nucleation, through variation of the [PdCl4]2- and ferrocene concentrations in the bulk of th

In concentrated solutions of aqueous RbCl, all of the Rb+ and Cl– ions exist as contact ion pairs. This full structural assessment is derived from the refinement of three independent experimental measurements: the Rb and Cl K-edge X-ray absorption fine structure (XAFS) and the X-ray diffraction spectra (XRD). This simultaneous refinement of the XAFS and XRD data provides high accuracy since each m

X-ray diffraction measurements of liquid water are reported at pressures up to 360 MPa corresponding to a density of 0.0373 molecules per Å3. The measurements were conducted at a spatial resolution corresponding to Qmax = 16 Å-1. The method of data analysis and measurement in this study follows the earlier benchmark results reported for water under ambient conditions having a density of 0.0333 mol

For ∼50 years mixtures of cobalt(II) and manganese(II) acetates with sodium bromide or hydrobromic acid in acetic acid have been used as catalysts for the homogeneous aerobic oxidation of alkylaromatic compounds. They are known to be stable mixtures. While characterizing this mixture via EXAFS, it was thus surprising to observe an unexpected change in the color of the reaction mixture from deep bl

The structure and chemical state of supported Pd nanoparticles in contact with H 2 in the aqueous phase have been explored by X-ray absorption spectroscopy to better understand their surface reactivity in polar condensed media. The Pd-Pd distances at substantial H 2 pressures indicate the presence of sorbed hydrogen and point to the presence of Pd hydrides, proving that such nanoparticles are har

We present a new methodology involving the simultaneous refinement of both x-ray absorption and x-ray diffraction spectra (x-ray absorption/diffraction structural refinement, XADSR) to study the hydration and ion pair structure of CaCl2 and RbBr salts in concentrated aqueous solutions. The XADSR method combines the x-ray absorption fine structure (XAFS) spectral analysis of both the cation and ani

Steady-state and picosecond time-resolved X-ray absorption spectroscopy is used to study the ground and lowest triplet states of [ReX(CO) 3 (bpy)] n+ , X = Etpy (n = 1), Cl, or Br (n = 0). We demonstrate that the transient spectra at both the Re L 3 -and Br K-edges show the emergence of a pre-edge feature, absent in the ground-state spectrum, which is associated with the electron hole created in

We use ultrafast x-ray absorption spectroscopy to determine the solvent structure change upon laser abstraction of the electron from I. The transition from hydrophilic to hydrophobic occurs over 4 ps during which a transient I-OH2 species is formed.

An X-ray absorption fine-structure spectroscopy (XAFS) cell that is suitable for solution-phase studies of the light elements in the series from Na+ and Ca2+ is described. This cell has an ultra-short pathlength that can be remotely adjusted using a miniature stepper-motor drive and thereby readily provides transmission pathlengths in the range from submicrometer to several hundred micrometers. Th

We show, through a combination of density function theory-based molecular dynamics simulations (DFT-MD) and experimental X-ray absorption fine structure spectroscopy (XAFS) studies, that the iodate ion (IO 3 -) contains a local region that is strongly hydrated as a cation. The local region adjoining the I atom is sufficiently electropositive that three hydrating waters are oriented with their O at

Picosecond and femtosecond X-ray absorption spectroscopy is used to probe the changes of the solvent shell structure upon electron abstraction of aqueous iodide using an ultrashort laser pulse. The transient L 1,3 edge EXAFS at 50 ps time delay points to the formation of an expanded water cavity around the iodine atom, in good agreement with classical and quantum mechanical/molecular mechanics (

Meeting adherence is an important element of compliance in treatment programmes. It is influenced by several factors one being self-efficacy. We aimed to investigate the association between self-efficacy and meeting adherence and other factors of importance for adherence among patients with alcohol and drug addiction who were undergoing an intensive lifestyle intervention. The intervention consistMeeting adherence is an important element of compliance in treatment programmes. It is influenced by several factors one being self-efficacy. We aimed to investigate the association between self-efficacy and meeting adherence and other factors of importance for adherence among patients with alcohol and drug addiction who were undergoing an intensive lifestyle intervention. The intervention consist

We present the extension of time-resolved optical pump/x-ray absorption spectroscopy (XAS) probe experiments towards data collection at MHz repetition rates. The use of a high-power picosecond laser operating at an integer fraction of the repetition rate of the storage ring allows exploitation of up to two orders of magnitude more x-ray photons than in previous schemes based on the use of kHz lase

We review our recent studies of excited state structures and dynamics of chemical and biological systems with pico- and femtosecond X-ray absorption spectroscopy in the liquid phase.

We present ultrafast x-ray emission studies of photoexcited aqueous iron tris-bipyridine with 70 ps temporal resolution to monitor the spin state changes in this spin-crossover complex.

Understanding the initial steps during ultrafast molecular reactions involving large spin state changes is a vital goal in structural dynamics research. These involve knowledge of the geometric structure of the system. Ultrafast X-ray absorption spectroscopy with 50-100 picosecond time resolution establishes the geometric structure of the short-lived (τ = 0:6 ns) high spin state. Here we focus on

(Figure Presented) Ultrafast spin probe: A short-lived transient species of light-excited [Fe(bpy) 3 ] 2+ (bpy = 2,2′-bipyridine) shows geometry variations that correspond to excitation to a high-spin state, in which the spin momentum of Fe" has now been directly determined to be S = 2 by spin-sensitive ultrafast X-ray emission spectroscopy.

The L3 X-ray absorption spectrum of aqueous iodide is reported, and its EXAFS is compared to theoretical spectra reconstructed from the radial distribution function of the iodide hydration obtained from classical, hybrid Quantum Mechanics Molecular Mechanics, (QM/MM) and full quantum (density functional theory, DFT) molecular dynamics simulations. Since EXAFS is mainly sensitive to short distances

Ultrafast X-ray absorption spectroscopy is a powerful tool to observe electronic and geometric structures of short-lived reaction intermediates. The ab initiofeff9 code is applied to simulate the Pt L3-edge XANES spectrum of the photocatalytic diplatinum molecule [Pt2(P2O5H2)4]4− and the photo-induced changes that occur therein. The spectra are interpreted within a XAFS-like scattering theoretical