## Characterization of water dissociation on α-Al2O3(1102)

- 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 lowThe 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.…

Author: | Jonas Wirth, Harald Kirsch, Sebastian Wlosczyk, Yujin Tong, Peter SaalfrankORCiDGND, Richard Kramer Campen |
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URN: | urn:nbn:de:kobv:517-opus4-394497 |

Subtitle (German): | theory and experiment |

Series (Serial Number): | Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe (320) |

Document Type: | Postprint |

Language: | English |

Date of first Publication: | 2016/04/18 |

Year of Completion: | 2016 |

Publishing Institution: | Universität Potsdam |

Release Date: | 2017/03/31 |

Pagenumber: | 11 |

First Page: | 14822 |

Last Page: | 14832 |

Source: | Phys.Chem.Chem.Phys. (2016) Nr. 18, S. 14822-14832. - DOI: 10.1039/C6CP01397J |

Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Chemie |

Dewey Decimal Classification: | 5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften |

Peer Review: | Referiert |

Publication Way: | Open Access |

Grantor: | RSC |

Licence (English): | Creative Commons - Attribution 3.0 unported |