Kyoto University · Physics and Astronomy
Professor Bernd Winter's research lab specializes in the electronic structure of liquids and aqueous interfaces, with a focus on water and its solutions. Using advanced photoelectron spectroscopy techniques—particularly liquid microjet methods combined with synchrotron radiation—the lab investigates valence and core-level electronic states of water, hydronium (H₃O⁺), hydroxide (OH⁻), and solvated ions. Their work reveals how solvent effects, such as electronic polarization and hydrogen bonding, influence ionization energies and electronic transitions in the liquid phase. The lab also explores the interplay between electronic and geometric structure in nanoscale clusters, especially copper clusters, to understand their stability and reactivity.
Figures are computed from collected data and may differ slightly.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotoemission from Liquid Aqueous SolutionsBernd Winter and Manfred FaubelView Author Information Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Strasse 2A, D-12489 Berlin, Germany Max-Planck-Institut für Dynamik und Selbstorganisation, Bunsenstrasse 10, D-37073 Göttingen, Germany Cite this: Chem. Rev. 2006, 106, 4, 1176–1211Publication Date (Web):March 8, 2006Publication History Received9 August 2005Published online8 Marc
The valence band photoelectron spectra of liquid water (H2O and D2O) are studied in the photon energy range from hν = 60 to 120 eV. The experiments use a 6 μm diameter liquid-jet free vacuum surface at the MBI undulator beamline of the synchrotron radiation facility BESSY. Photoelectron emission from all four valence molecular orbitals (MOs) is observed. In comparison to those of the gas phase, the peaks are significantly broadened and shifted to lower binding energies by about 1.5 eV. This is a
The authors report on photoelectron emission spectroscopy measurements of the oxygen 1s orbital of liquid water, using a liquid microjet in ultrahigh vacuum. By suitably changing the soft x-ray photon energy, within 600-1200 eV, the electron probing depth can be considerably altered as to either predominantly access the surface or predominantly bulk water molecules. The absolute probing depth in liquid water was inferred from the evolution of the O1s signal and from comparison with aqueous salt
Copper clusters in the 50- to 100-atom size range are found to exhibit electronic shell structure as well as icosahedral geometry. Clusters corresponding to filled shells have minimum intensity in near-threshold photoionization mass spectra, implying that they have locally higher ionization potentials than other cluster sizes. The chemical stability of these clusters is illustrated by a reduced reactivity towards O2. Cluster geometry is probed via the equilibrium reactions with H2O: Clusters hav
Photoelectron spectroscopy combined with the liquid microjet technique enables the direct probing of the electronic structure of aqueous solutions. We report measured and calculated lowest vertical electron binding energies of aqueous alkali cations and halide anions. In some cases, ejection from deeper electronic levels of the solute could be observed. Electron binding energies of a given aqueous ion are found to be independent of the counterion and the salt concentration. The experimental resu
The electronic structure of hydrated H3O+ and OH- is probed in a water jet by photoelectron spectroscopy employing 100 eV photons. The first ionization potential for OH- at 9.2 eV and the second ionization potential for H3O+ at 20 eV are resolved, corresponding to the removal of an electron from the 2ppi highest occupied molecular orbital and from the 1e orbital, respectively. These assignments are supported by present computational results based on a combination of molecular dynamics and ab ini
We report photoelectron measurements and molecular dynamics (MD) simulations with a polarizable force field of surface-active tetrabutylammonium iodide (TBAI) in aqueous solution. Photoemission is studied for a photon energy of 100 eV, using a 6-μm-diameter liquid jet. Surfactant activity of the TBAI salt at the solution surface is proved by a dramatic (×70) increase of the I-(4d) signal, as compared to that of a NaI aqueous solution for identical salt concentrations. Completion of the segregati
The absolute-scale electronic energetics of liquid water and aqueous solutions, both in the bulk and at associated interfaces, are the central determiners of water-based chemistry. However, such information is generally experimentally inaccessible. Here we demonstrate that a refined implementation of the liquid microjet photoelectron spectroscopy (PES) technique can be adopted to address this. Implementing concepts from condensed matter physics, we establish novel all-liquid-phase vacuum and equ
Watching electrons swarm ammonia Liquid ammonia is unusual in its capacity to host electrons in stable solution, with vivid blue and bronze colors signifying the low- and high-concentration regimes, respectively. Buttersack et al. used photoelectron spectroscopy and accompanying theoretical simulations to track the precise energetic changes that ensued as steadily rising quantities of electrons were introduced by dissolved lithium, sodium, or potassium (see the Perspective by Isborn). The result
It has only recently become possible to use photoelectron spectroscopy (PES) to study the electronic structure of highly volatile aqueous surfaces. Here, we review current X-ray PES and related resonant Auger-electron decay and intermolecular Coulomb decay investigations in solution, which aim at understanding the solute–water, water–water, and solute–solute interactions at the microscopic level. Systems that will be discussed include neat liquid water, and aqueous solutions of hydroxide, hydron
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