Berlin 2008 – wissenschaftliches Programm

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SYSA: Symposium Tayloring Organic Interfaces: Molecular Structures and Applications

SYSA 5: Poster Session SYSA

SYSA 5.19: Poster

Dienstag, 26. Februar 2008, 14:30–20:00, Poster A

An Infrared Spectroscopy and X-ray Diffraction Study of the medium length n-Hexadecanol solidified in mesoporous silicon — Anke Henschel, •René Berwanger, Rolf Pelster, Klaus Knorr, and Patrick Huber — Saarland University, Saarbruecken, Germany

The conformation and arrangement of the n-alcohol C₁₆H₃₃OH confined in tubular pores of porous silicon (mean pore diameter 10nm, pore length 70 µm) is investigated by combined Infrared Spectroscopy and X-Ray Diffraction measurements. The phase behaviour is reminiscent of the one found for the linear n-alkanes confined in mesoporous silicon¹: the long axes of the molecules are oriented perpendicular to the pore axes. About the long axes of the pores we find a four-fold symmetry of the diffraction pattern, coinciding with the symmetry of the silicon matrix. The confined alcohol exhibits six dominant domains.
We find distinct changes in the vibration characteristics, in the structure factor as well as the phase transition temperatures of the confined alcohol as compared to the bulk phase. The phase sequence in the pores is liquid, Rotator and crystalline. The melting and freezing transitions are reduced by 20 K.
¹A. Henschel, T. Hofmann, P. Huber, K. Knorr, Phys. Rev. E 75, 021607 (2007)