Aqueous-phase behavior of glyoxal and methylglyoxal observed with carbon and oxygen K-edge X-ray absorption spectroscopy

Abstract. Glyoxal (CHOCHO) and methylglyoxal (CH3C(O)CHO) are well-known components of atmospheric particles their properties can impact chemistry cloud formation. To get information on hydration states in aqueous solutions how they affected by the addition inorganic salts (sodium chloride (NaCl) sodium sulfate (Na2SO4)), we applied carbon oxygen K-edge X-ray absorption spectroscopy (XAS) transmission mode. The recorded C spectra show that glyoxal is completely hydrated dilute solutions, line with previous studies. For methylglyoxal, supported quantum chemical calculations identified not only C–H, C=O C–OH bonds, but also fingerprints C–OH(CH2) C=C bonds. relatively low intensity transitions implies monohydrated form favored solutions. Instead, spectral stronger regions where products aldol condensation enol tautomers monohydrates contribute. was found to introduce very minor changes energies relative intensities observed features, indicating XAS near-edge region sensitive these intermolecular organic–inorganic interactions at studied concentrations. structures an environment support uptake compounds aerosol phase presence water contribution secondary organic