Dresden 2009 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 6: Critical phenomena and phase transitions

DY 6.8: Vortrag

Montag, 23. März 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.