Dissociation of Sulfuric Acid in Aqueous Solution: Determination of the Photoelectron Spectral Fingerprints of H2SO4, HSO4–, and SO42– in Water

In the work described here, the electronic structure of sulfuric acid in water is explored by liquid-jet photoelectron spectroscopy. From the S2p photoelectron spectra of H2SO4 (aq), measured over a large concentration range and aided by previously reported HSO4–/SO42- and HSO4–/H2SO4 concentration ratios in the bulk solution, we obtain detailed electronic structure information of each species. Comparing our results with previous studies on the dissociation of nitric acid, we argue that the solvation structure of H2SO4 (aq) changes around 5–7 M concentration, at which point a dramatic change in both the HSO4– photoelectron peak width and binding energy occurs.