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HL: Fachverband Halbleiterphysik

HL 26: Interfaces and Surfaces

HL 26.5: Talk

Monday, March 14, 2011, 17:00–17:15, POT 06

Adsorption of Methanol on Lithium niobate (0001) — •Arthur Riefer, Simone Sanna, and Wolf Gero Schmidt — Theoretische Physik, Universität Paderborn, 33095 Paderborn, Germany

Lithium niobate (LN) is a ferroelectric material with a huge range of applications. While the bulk properties of LN are exploited in optical and acoustic devices, the physics on the different oriented surfaces allows the realization of molecular detectors and other devices at nanoscale level. Temperature programmed desorption measurements of polar molecules, such as Water, Methanol [1], and 2-Propanol [2], on the (0001) LN surfaces show stronger adsorption of these molecules on the positive surface. The mechanisms behind the bonding are still not clear. Recently, structural models for the negative and positive (0001) surface of LN have been proposed on the basis of Density Functional Theory (DFT) calculations. Here, we investigate the behavior of Methanol on the LN surfaces by means of DFT in the Generalized Gradient approximation (GGA). As a first step, we calculate the potential energy surface (PES) for both orientations. We find the preferred position of an adsorption of Methanol near the Oxygen atoms on the positive or near the Lithium atoms on the negative surface, respectively and a bonding-energy difference of about 0.5 eV between the two sites. Also, we investigate the possibility of a dissociation of the molecule on the LN surfaces.

[1] J. Garra et al., Surface Science 603 (2009) 1106 - 1114

[2] Y. Yun et al., J. Phys. Chem. C 111 (2007) 13951-13956