Photoemission from Liquid Aqueous Solutions

Winter, Bernd; Faubel, Manfred

doi:10.1021/cr040381p

Cited by 467 publications

(656 citation statements)

References 272 publications

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“…Details on this technique can be found e.g. in reference 26 . The liquid micro-jet (∅ ≈ 20 μm, flow rate ≈ 0.5 ml/min (≈ 26.5 m/s), T ≈ 283 K) is injected through a glass nozzle into an evacuated analysis chamber.…”

Section: Methodsmentioning

confidence: 99%

Alcohols at the aqueous surface: chain length and isomer effects

Walz

Werner

Ekholm

et al. 2016

Phys. Chem. Chem. Phys.

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Surface-active organic molecules at the liquid-vapor interface are of great importance in atmospheric science. Therefore, we studied the surface behavior of alcohol isomers with different chain lengths (C4-C6) in aqueous solution with surfaceand chemically sensitive X-ray photoelectron spectroscopy (XPS), which reveals information about the surface structure on a molecular level. Gibbs free energies of adsorption and surface concentrations are determined from the XPS results using a standard Langmuir adsorption isotherm model. The free energies of adsorption, ranging from around -15 to -19 kJ/mol (C4-C6), scale linearly with the number of carbon atoms within the alcohols with ΔGAds per -CH2-≈ -2 kJ/mol. While for the linear alcohols, surface concentrations lie around 2.4 x 10 14 molecules/cm 2 at the bulk concentrations where monolayers are formed, the studied branched alcohols show lower surface concentrations of around 1.6 x 10 14 molecules/cm 2 , both of which are in line with the molecular structure and their orientation at the interface. Interestingly, we find that there is a maximum in the surface enrichment factor for linear alcohols at low concentrations, which is not observed for the shorter branched alcohols. This is interpreted in terms of a cooperative effect, which we suggest to be the result of more effective van der Waals interactions between the linear alcohol alkyl chains at the aqueous surface, making it energetically even more favorable to reside at the liquid-vapor interface.

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Section: Methodsmentioning

confidence: 99%

Alcohols at the aqueous surface: chain length and isomer effects

Walz

Werner

Ekholm

et al. 2016

Phys. Chem. Chem. Phys.

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“…32,54,72 Water is an insulator with strong local distortions, though topologically similar to that of ice phases. [1][2][3] Correspondingly the DOS curve is composed of very localized states (Fig. 5).…”

Section: View Article Onlinementioning

confidence: 99%

“…We will now first discuss the experimental studies whereby the electronic structures of gas, water, and ice phases were investigated. 2,[15][16][17][18][19][20][21][22][23][24][25] Shibaguchi and co-workers investigated the electronic structure of ice by means of a combination of X-ray photoemission spectroscopy (XPS), Ultraviolet photoemission spectroscopy (UPS), and optical absorption spectroscopy, and obtained a band gap of 8.75 eV. 17 Painter and co-workers measured the reflectance of liquid water between 1050 and 3000 Å 16 and found that the imaginary index of refraction starts at around 7.1 eV.…”

Section: Introductionmentioning

confidence: 99%

The accurate calculation of the band gap of liquid water by means of GW corrections applied to plane-wave density functional theory molecular dynamics simulations

Fang

Koster

et al. 2015

Phys. Chem. Chem. Phys.

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Knowledge about the intrinsic electronic properties of water is imperative for understanding the behaviour of aqueous solutions that are used throughout biology, chemistry, physics, and industry. The calculation of the electronic band gap of liquids is challenging, because the most accurate ab initio approaches can be applied only to small numbers of atoms, while large numbers of atoms are required for having configurations that are representative of a liquid. Here we show that a high-accuracy value for the electronic band gap of water can be obtained by combining beyond-DFT methods and statistical time-averaging. Liquid water is simulated at 300 K using a plane-wave density functional theory molecular dynamics (PW-DFT-MD) simulation and a van der Waals density functional (optB88-vdW).After applying a self-consistent GW correction the band gap of liquid water at 300 K is calculated as 7.3 eV, in good agreement with recent experimental observations in the literature (6.9 eV). For simulations of phase transformations and chemical reactions in water or aqueous solutions whereby an accurate description of the electronic structure is required, we suggest to use these advanced GW corrections in combination with the statistical analysis of quantum mechanical MD simulations.

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“…Only after Faubel et al developed the liquid beam technique in vacuum also volatile liquids like water could be investigated with photoelectron spectroscopy in vacuum [5][6][7][8]. Since then, the chemical shift in the static ESCA approach has also been a particularly powerful observable for probing electron densities and molecular orbital energies in different liquid molecular environments [9,10].…”

Section: Esca and Photoelectron Spectroscopy Near Liquid Interfaces Xmentioning

confidence: 99%

Ultrafast electronic spectroscopy for chemical analysis near liquid water interfaces: concepts and applications

et al. 2009

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Electron spectroscopy for chemical analysis (ESCA) being conceptually a photoelectron spectroscopy is established as a chemically specific probe mostly for surface analysis. Liquid phase ESCA for volatile liquids has become possible through the development of the liquid microjet technique in vacuum enabling the measurement of liquid interface photoelectron emission at the high vapor pressure of volatile liquids. Recently we have been able to add the dimension of time to the liquid interface ESCA technique employing high-harmonics soft X-ray and UV/near IR femtosecond pulses in combination with liquid water micro beams in vacuum. The concepts as well as technical details are outlined and several characteristic applications are high-

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Photoemission from Liquid Aqueous Solutions

Cited by 467 publications

References 272 publications

Alcohols at the aqueous surface: chain length and isomer effects

Alcohols at the aqueous surface: chain length and isomer effects

The accurate calculation of the band gap of liquid water by means of GW corrections applied to plane-wave density functional theory molecular dynamics simulations

Ultrafast electronic spectroscopy for chemical analysis near liquid water interfaces: concepts and applications

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