Finite size and interfacial effects in liquid crystals confined to random porous matrices: Broadband dielectric spectroscopy investigations

The dielectric behavior of confined 8CB has been investigated by means of u ltra broad-band dielectric spectroscopy. New features such as two relaxatio n processes with characteristic frequencies around (1-10) Hz and 100 kHz, w hich are absent in bulk liquid crystals, were observed in confined geometri es. These processes arise due to the relaxation of interfacial polarization at pore wall-liquid crystal interface and the hindered rotation of the mol ecules near the interface respectively. Two other bulk like modes due to th e rotation of polar molecules around their short axis and due to tumbling o f molecules were also observed in confined geometries. We also investigated these processes in the supercooled state. All observed processes are non D ebye like.