Abstract The chemistry and physics of charged interfaces is regulated by the structure electrical double layer (EDL). Herein we quantify average thickness Stern at silica (SiO 2 ) nanoparticle/aqueous electrolyte interface as a function NaCl concentration following direct measurement nanoparticles’ surface potential X‐ray photoelectron spectroscopy (XPS). We find compresses (becomes thinner) increased. This finding provides simple intuitive picture EDL that explains concurrent increase in...

The structure of the electrical double layer has been debated for well over a century, since it mediates colloidal interactions, regulates surface structure, controls reactivity, sets capacitance, and represents central element electrochemical supercapacitors. potential such surfaces generally exceeds electrokinetic potential, often substantially. Traditionally, Stern nonspecifically adsorbed ions invoked to rationalize difference between these two potentials; however, inability directly...

In one of the most commonly used phenomenological descriptions electrical double layer, a charged solid surface and diffuse region mobile ions are separated from each other by thin charge-depleted Stern layer. The layer acts as capacitor that improves classical Gouy–Chapman model increasing magnitude potential limiting maximal counterion concentration. We show very similar Stern-like properties emerge naturally adding nonelectrostatic hydration repulsion to electrostatic Coulomb potential....

Insight into ion behavior at mixed organic/aqueous liquid surfaces is crucial for understanding the chemistry of atmospheric aerosols, which frequently contain mixtures water, electrolytes, and organics. The addition 1-butanol to an aqueous potassium iodide solution modifies interfacial profile ions liquid−vapor interface. Our experiments probe atomic composition surface with ambient pressure X-ray photoelectron spectroscopy. Photoelectron kinetic energies are varied produce a depth...

Nanowires composed of the thermoelectric material Bi2Te3 were synthesized on highly oriented pyrolytic graphite (HOPG) electrodes using electrochemical step edge decoration (ESED) method. Nanowire synthesis was initiated by applying a voltage pulse −0.75 V versus SCE for 5 ms to an HOPG electrode in aqueous solution containing both Bi3+ and TeO22-, thereby producing nuclei at edges. electrodeposited onto these cyclic electrodeposition−stripping scheme that involved electrodeposition...

The CO binding behavior to gold particles supported on MgO thin films has been analyzed with scanning tunneling microscopy (STM) and infrared spectroscopy (IRAS). ad-particles accommodate excess electrons that originate either from a charge transfer through the oxide film or local interaction electron-rich defects act as Au nucleation centers. enhanced electron density in aggregates affects both spatial distribution vibrational properties of adsorbed species. Whereas preferential attachment...

X-Ray photoemission spectroscopy operating under ambient pressure conditions is used to probe ion distributions throughout the interfacial region of a free-flowing aqueous liquid micro-jet 6 M potassium fluoride. Varying energy ejected photoelectrons by carrying out experiments as function X-ray wavelength measures composition aqueous-vapor at various depths. The F(-) K(+) atomic ratio equal unity depth 2 nm. experimental profiles are compared with results classical molecular dynamics...

The nucleation and electronic structure of vapor-deposited Au on hydroxylated MgO(001) surfaces has been investigated under ultrahigh vacuum conditions. Hydroxylated with two different hydroxyl coverages, 0.4 1 monolayer, respectively, were prepared by exposure to water (D(2)O) at room temperature. Scanning tunneling microscopy experiments show significantly higher gold particle densities smaller sizes the MgO surface as compared deposited clean MgO(001). Infrared spectroscopy X-ray...

We show that the surface potential at a water–oxide nanoparticle (NP) interface, long considered an immeasurable direct quantity, can be measured by X-ray photoelectron spectroscopy (XPS) from liquid microjet. This new method does not require priori knowledge of particles' structure or ion distribution throughout electrical double layer for its interpretation and applied to any colloidal suspension independent composition, particle size shape, solvent. demonstrate application aqueous...

Abstract The chemistry and physics of charged interfaces is regulated by the structure electrical double layer (EDL). Herein we quantify average thickness Stern at silica (SiO 2 ) nanoparticle/aqueous electrolyte interface as a function NaCl concentration following direct measurement nanoparticles’ surface potential X‐ray photoelectron spectroscopy (XPS). We find compresses (becomes thinner) increased. This finding provides simple intuitive picture EDL that explains concurrent increase in...

We describe the preparation by electrodeposition of arrays lead telluride (PbTe) nanowires using lithographically patterned nanowire (LPNE) method. PbTe had a rectangular cross-section with adjustable width and height ranging between 60-400 nm (w) 20-100 (h). The characterization these X-ray diffraction, transmission electron microscopy scanning microscopy, atomic force photoelectron spectroscopy (XPS) is reported. were electrodeposited cyclic electrodeposition-stripping technique that...

Depth-resolved ion spatial distributions of nitrate and nitrite anions in aqueous solution have been quantitatively measured using X-ray photoemission spectroscopy on a 15 microm liquid jet containing 3 M NaNO(3), NaNO(2), or an equimolar mixture the two. The surface region, which extends to photoelectron kinetic energies 400-500 eV, is partially depleted relative bulk concentration. solutions exhibit similar depth-dependent anion profiles. results presented here are compared with recent...

The chemistry of Br species associated with sea salt ice and aerosols has been implicated in the episodes ozone depletion reported at Arctic sunrise. However, Br(-) is only a minor component salt, which Br(-)/Cl(-) molar ratio approximately 0.0015. Sea complex mixture many different species, NaCl as primary component. In recent years experimental theoretical studies have enhancement large, more polarizable halide ion liquid/vapor interface corresponding aqueous alkali solutions. proposed...

A new liquid microjet endstation designed for ultraviolet (UPS) and X-ray (XPS) photoelectron, partial electron yield absorption (XAS) spectroscopies at the Swiss Light Source is presented. The endstation, which based on a Scienta HiPP-2 R4000 spectrometer, first capable of operating in vacuum ambient pressures up to equilibrium vapor pressure water room temperature. In addition, energy analyzer this allows XPS measurements 7000 eV kinetic that will enable electronic structure bulk solutions...

The surface charge density and potential of oxide surfaces are to a large extent regulated by the co- counterion distributions in electrical double layer. Here we study effect different anions (Cl–, Br–, I–, HCOO–, NO3–) sodium electrolytes cations (Li+, Na+, K+, Cs+) chloride on relative colloidal nanometer sized silica (SiO2) as function electrolyte concentration bulk pH using potentiometric titrations, attenuated total reflection–Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray...

Using in-situ X-ray photoelectron spectroscopy at the vapor-water interface, affinity of nanometer-sized silica colloids to adsorb interface is shown depend on colloid surface charge density. In aqueous suspensions pH 10 corrected Debye-Hückel theory for complexation calculations predict that smaller have increased negative density originates from enhanced screening deprotonated silanol groups (≡Si-O(-)) by counterions in condensed ion layer. The results an electrostatic repulsion seen a...

Hydroxylation of MgO surfaces has been studied from UHV to mbar pressure for MgO(001) films different thickness grown on Ag(001) by X-ray photoelectron spectroscopy, infrared reflection absorption and density functional theory calculations. In agreement with earlier studies single crystals, a threshold water the order 10−4 is found extensive hydroxylation thick, bulklike films. Decreasing film shifts lower values, being 10−6 in limit 2 monolayer MgO(001)/Ag(001). This result explained basis...

The influence of surface hydroxylation on nucleation and sintering gold nanoparticles was studied by comparison Au deposition thermal ideally terminated MgO(001) hydroxylated MgO thin films, respectively. A combination different spectroscopic techniques (TDS, XPS, IRAS) allows to establish a correlation between the degree stability atoms clusters. Hydroxyl groups destabilize at 90 K; however, they enhance small clusters toward higher temperature.

Ice plays a key role in the environment, and ice-air interface influences heterogeneous chemical reactions between snowpack or cirrus clouds surrounding air. Soluble gases have been suspected to affect topmost, disordered layer on ice (often referred as quasiliquid layer, QLL). Changes are especially expected hydrogen-bonding structure of water presence solutes at surface. Here, we used ambient-pressure X-ray photoelectron spectroscopy (XPS) detect acetic acid surface 230-240 K under...

It has only recently become possible to use photoelectron spectroscopy (PES) study the electronic structure of highly volatile aqueous surfaces. Here, we review current X-ray PES and related resonant Auger-electron decay intermolecular Coulomb investigations in solution, which aim at understanding solute–water, water–water, solute–solute interactions microscopic level. Systems that will be discussed include neat liquid water, solutions hydroxide, hydronium, salts amino acids. From observed...

Breathing: A simple and intuitive approach relates changes in bond lengths of core-hole ionized states to the extent vibrational fine structure, or Franck–Condon broadening (ΔE), X-ray photoelectron spectra ionic compounds. For extreme case a monolayer MgO on Ag(100), difference compared bulk reflects different binding situation supported oxide (see picture, r=MgO distance). Detailed facts importance specialist readers are published as "Supporting Information". Such documents peer-reviewed,...

A new apparatus for attosecond time-resolved photoelectron spectroscopy of liquids and gases is described. It combines a liquid microjet source with magnetic-bottle spectrometer an actively stabilized beamline. The permits venting pumping the interaction chamber without affecting low pressure in flight tube. This separation has been realized through sliding skimmer plate, which effectively seals tube its closed position functions as differential stage open position. high-harmonic photon...

Despite the ubiquitous nature of aqueous solutions across chemical, biological and environmental sciences our experimental understanding their electronic structure is rudimentary-qualitative at best. One most basic seemingly straightforward properties solutions-ionization energies-are (qualitatively) tabulated water-air interface for a mere handful solutes, manner in which these results are obtained assume behave like gas photoelectron experiment (where vacuum levels solution analyzer...

We show that attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy can be used to determine the surface charge density (SCD) of colloidal silica nanoparticles (NPs) in aqueous solution. identify Si-O stretch vibrations neutral bound silanol, ≡Si-OH, and deprotonated group, ≡Si-O(-). The position Si-(OH) vibration is shown directly correlate with NPs SCD as determined by traditional potentiometric titrations, shifting lower wavenumber (cm(-1)) increasing origin this...