Publications by authors named "Remi Dupuy"

The interface of the oceans and aqueous aerosols with air drives many important physical and chemical processes in the environment, including the uptake of CO by the oceans. Transport across and reactions at the ocean-air boundary are in large part determined by the chemical composition of the interface, , the first few nanometers into the ocean. The main constituents of the interface, besides water molecules, are dissolved ions and amphiphilic surfactants, which are ubiquitous in nature.

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The multi-phase oxidation of S(IV) plays a crucial role in the atmosphere, leading to the formation of haze and severe pollution episodes. We here contribute to its understanding on a molecular level by reporting experimentally determined pK values of the various S(IV) tautomers and reaction barriers for SO formation pathways. Complementary state-of-the-art molecular-dynamics simulations reveal a depletion of bisulfite at low pH at the liquid-vapor interface, resulting in a different tautomer ratio at the interface compared to the bulk.

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We have investigated the surfactant properties of phenol in aqueous solution as a function of pH and bulk concentration using liquid-jet photoelectron spectroscopy (LJ-PES) and surface tension measurements. The emphasis of this work is on the determination of the Gibbs free energy of adsorption and surface excess of phenol and its conjugate base phenolate at the bulk p (9.99), which can be determined for each species using photoelectron spectroscopy.

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Article Synopsis
  • Molecules in solvation shells have unique properties that differ from those of the solvent in bulk and can influence chemical reactions.
  • X-ray-based spectroscopies are commonly used to examine these properties but often fail to selectively analyze solvation-shell molecules.
  • New "non-local" X-ray processes, like intermolecular Coulombic decay (ICD), offer a promising way to study the first solvation shell of cations and to measure water molecules' electron binding energies more effectively.
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We present a combined Langmuir-Pockels trough and ambient pressure X-ray photoelectron spectroscopy (APXPS) study of the compression of stearic acid surfactant layers on neat water. Changes in the packing density of the molecules are directly determined from C 1s and O 1s APXPS data. The experimental data are fit with a 2D model for the stearic acid coverage.

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Correction for 'Photoelectron angular distributions as sensitive probes of surfactant layer structure at the liquid-vapor interface' by Rémi Dupuy , , 2022, , 4796-4808, https://doi.org/10.1039/D1CP05621B.

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Article Synopsis
  • Photoelectron spectroscopy (PES) is utilized to study liquid-vapor interfaces, revealing how molecules and ions arrange themselves in the first few nanometers of a solution, crucial for fields like environmental chemistry and fundamental physics.
  • Key topics explored include the distribution of surfactants, their self-assembly, and the behavior of ion double layers at the liquid-vapor interface, leveraging PES's chemical specificity and surface sensitivity.
  • The text discusses the challenges of measuring photoelectron angular distributions (PADs) to obtain depth information, highlighting the impact of electron scattering (both elastic and inelastic) on data accuracy.
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The characterization of liquid-vapor interfaces at the molecular level is an important underpinning for a basic understanding of fundamental heterogeneous processes in many areas, such as atmospheric science. Here we use X-ray photoelectron spectroscopy to study the adsorption of a model surfactant, octanoic acid, at the water-gas interface. In particular, we examine the information contained in photoelectron angular distributions and show that information about the relative depth of molecules and functional groups within molecules can be obtained from these measurements.

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Liquid-vapor interfaces, particularly those between aqueous solutions and air, drive numerous important chemical and physical processes in the atmosphere and in the environment. X-ray photoelectron spectroscopy is an excellent method for the investigation of these interfaces due to its surface sensitivity, elemental and chemical specificity, and the possibility to obtain information on the depth distribution of solute and solvent species in the interfacial region. In this Perspective, we review the progress that was made in this field over the past decades and discuss the challenges that need to be overcome for investigations of heterogeneous reactions at liquid-vapor interfaces under close-to-realistic environmental conditions.

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