10.1021/acs.jpclett.7b00273.s001 Matias R. Fagiani Matias R. Fagiani Xiaowei Song Xiaowei Song Sreekanta Debnath Sreekanta Debnath Sandy Gewinner Sandy Gewinner Wieland Schöllkopf Wieland Schöllkopf Knut R. Asmis Knut R. Asmis Florian A. Bischoff Florian A. Bischoff Fabian Müller Fabian Müller Joachim Sauer Joachim Sauer Dissociative Water Adsorption by Al<sub>3</sub>O<sub>4</sub><sup>+</sup> in the Gas Phase American Chemical Society 2017 Dissociative Water Adsorption cm D 2 O Al 2 O 3 phases gas phase model systems Gas Phase water molecules vibrational spectra assignment photodissociation spectra hydroxyl groups minimum-energy structures DFT dissociative water adsorption Al 3 O 4 use cryogenic ion trap vibrational spectroscopy region 2017-03-06 12:50:27 Journal contribution https://acs.figshare.com/articles/journal_contribution/Dissociative_Water_Adsorption_by_Al_sub_3_sub_O_sub_4_sub_sup_sup_in_the_Gas_Phase/4725823 We use cryogenic ion trap vibrational spectroscopy in combination with density functional theory (DFT) to study the adsorption of up to four water molecules on Al<sub>3</sub>O<sub>4</sub><sup>+</sup>. The infrared photodissociation spectra of [Al<sub>3</sub>O<sub>4</sub>(D<sub>2</sub>O)<sub>1–4</sub>]<sup>+</sup> are measured in the O–D stretching (3000–2000 cm<sup>–1</sup>) as well as the fingerprint spectral region (1300–400 cm<sup>–1</sup>) and are assigned based on a comparison with simulated harmonic infrared spectra for global minimum-energy structures obtained with DFT. We find that dissociative water adsorption is favored in all cases. The unambiguous assignment of the vibrational spectra of these gas phase model systems allows identifying characteristic spectral regions for O–D and O–H stretching modes of terminal (μ<sub>1</sub>) and bridging (μ<sub>2</sub>) hydroxyl groups in aluminum oxide/water systems, which sheds new light on controversial assignments for solid Al<sub>2</sub>O<sub>3</sub> phases.