Dresden 2009 – wissenschaftliches Programm
MM 15.2: Vortrag
Dienstag, 24. März 2009, 10:45–11:00, IFW B
Crystallization Kinetics Dictate the Molecular Arrangement in Nanochannels — •Anke Henschel, Klaus Knorr, and Patrick Huber — Saarland University, Saarbruecken, Germany
We present an x-ray diffraction study on the crystallization of chain-like molecules (medium length n-alkanes and n-alcohols) in arrays of lined up, tubular silicon and silica channels (mean channel diameters of 10 nm)1−2.
The samples, prepared by capillary condensation or filling in the liquid state and subsequent cooling below the pore freezing point, exhibit diffraction patterns typical of significant, anisotropic orientation distributions of the pore crystals. The architectural principle common to all observed textures originates in a nano-scale version of the mechanism underlying the Bridgman technique of single crystal growth: Upon solidification of completely filled nanochannels the fastest, and hence dominant growth direction, propagates along the long axes of the channels and thereby dictates a distinct orientational arrangement of the molecular crystals.
(1) A. Henschel, T. Hofmann, P. Huber, K. Knorr, Phys. Rev. E 75, 021607 (2007).
(2) A. Henschel, P. Huber and K. Knorr, Phys. Rev. E 77, 042602 (2008).