Issue 22, 2016

Characterization of water dissociation on α-Al2O3(1[1 with combining macron]02): theory and experiment


The interaction of water with α-alumina (i.e. α-Al2O3) surfaces is important in a variety of applications and a useful model for the interaction of water with environmentally abundant aluminosilicate phases. Despite its significance, studies of water interaction with α-Al2O3 surfaces other than the (0001) are extremely limited. Here we characterize the interaction of water (D2O) with a well defined α-Al2O3(1[1 with combining macron]02) surface in UHV both experimentally, using temperature programmed desorption and surface-specific vibrational spectroscopy, and theoretically, using periodic-slab density functional theory calculations. This combined approach makes it possible to demonstrate that water adsorption occurs only at a single well defined surface site (the so-called 1–4 configuration) and that at this site the barrier between the molecularly and dissociatively adsorbed forms is very low: 0.06 eV. A subset of OD stretch vibrations are parallel to this dissociation coordinate, and thus would be expected to be shifted to low frequencies relative to an uncoupled harmonic oscillator. To quantify this effect we solve the vibrational Schrödinger equation along the dissociation coordinate and find fundamental frequencies red-shifted by more than 1500 cm−1. Within the context of this model, at moderate temperatures, we further find that some fraction of surface deuterons are likely delocalized: dissociatively and molecularly absorbed states are no longer distinguishable.

Graphical abstract: Characterization of water dissociation on α-Al2O3(1 [[1 with combining macron]] 02): theory and experiment

Supplementary files

Article information

Article type
29 Feb 2016
18 Apr 2016
First published
18 Apr 2016
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2016,18, 14822-14832

Author version available

Characterization of water dissociation on α-Al2O3(1[1 with combining macron]02): theory and experiment

J. Wirth, H. Kirsch, S. Wlosczyk, Y. Tong, P. Saalfrank and R. K. Campen, Phys. Chem. Chem. Phys., 2016, 18, 14822 DOI: 10.1039/C6CP01397J

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity