Dresden 2009 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 6: Critical phenomena and phase transitions
DY 6.8: Talk
Monday, March 23, 2009, 16:30–16:45, ZEU 118
Capillary Condensation and Hysteresis in Porous Silicon: Network Effects within Independent Pores — Sergej Naumov1, Alexey Khokhlov1, •Rustem Valiullin1, Jörg Kärger1, and Peter A. Monson2 — 1Department of Interface Physics, University of Leipzig, D-04103 Leipzig, Germany — 2Department of Chemical Engineering, University of Massachusetts, Amherst, MA 01003, USA
The ability to exert a significant degree of pore structure control in porous silicon materials has made them attractive materials for the experimental investigation of the relationship between pore structure, capillary condensation and hysteresis phenomena. Using both experimental measurements and a lattice gas model in mean field theory, we have investigated the role of pore size inhomogeneities and surface roughness on capillary condensation of N2 at 77 K in porous silicon with linear pores. Our results resolve some puzzling features of earlier experimental work. We find that this material has more in common with disordered materials such as Vycor glass than the idealized smooth-walled cylindrical pores discussed in the classical adsorption literature. We provide strong evidence that this behavior comes from the complexity of the processes within independent linear pores, arising from the pore size inhomogeneities along the pore axis, rather than from cooperative effects between different pores.