TY - JOUR
T1 - The surface composition of amino acid - halide salt solutions is pH-dependent
AU - Gopakumar, Geethanjali
AU - Unger, Isaak
AU - Saak, Clara Magdalena
AU - Öhrwall, Gunnar
AU - Naves de Brito, Arnaldo
AU - Rizuti da Rocha, Tulio Costa
AU - Nicolas, Christophe
AU - Caleman, Carl
AU - Björneholm, Olle
PY - 2022
Y1 - 2022
N2 - In atmospheric aerosol particles, the chemical surface composition governs both heterogenous chemical reactions with gas-phase species and the ability to act as nuclei for cloud droplets. The pH in aerosol particles is expected to affect these properties, but it is very challenging to measure the pH in individual droplets, precluding the investigation of its influence on the particle's surface composition. In this work, we use photoelectron spectroscopy to explore how the surface composition of aqueous solutions containing inorganic salt and amino acids changes as a function of pH. We observe a change by a factor of 4-5 of the relative distribution of inorganic ions at the surface of a liquid water jet, as a function of solution pH and type of amino acid in the solution. The driving forces for the surface enhancement or depletion are ion pairing and the formation of charged layers close to the aqueous surface.
AB - In atmospheric aerosol particles, the chemical surface composition governs both heterogenous chemical reactions with gas-phase species and the ability to act as nuclei for cloud droplets. The pH in aerosol particles is expected to affect these properties, but it is very challenging to measure the pH in individual droplets, precluding the investigation of its influence on the particle's surface composition. In this work, we use photoelectron spectroscopy to explore how the surface composition of aqueous solutions containing inorganic salt and amino acids changes as a function of pH. We observe a change by a factor of 4-5 of the relative distribution of inorganic ions at the surface of a liquid water jet, as a function of solution pH and type of amino acid in the solution. The driving forces for the surface enhancement or depletion are ion pairing and the formation of charged layers close to the aqueous surface.
U2 - 10.1039/d1ea00104c
DO - 10.1039/d1ea00104c
M3 - Article
AN - SCOPUS:85127631032
SN - 2634-3606
VL - 2
SP - 441
EP - 448
JO - Environmental Science: Atmospheres
JF - Environmental Science: Atmospheres
IS - 3
ER -