Relaxations in confinement as probed by solvation dynamics

Solvation dynamics data of the probe quinoxaline in the glass-forming liqui d 2-methyltetrahydrofuran (MTHF) is employed to study the orientational dyn amics of a liquid which is geometrically confined by porous glasses. In ord er to discriminate pure confinement from interfacial effects, we compare in detail the relaxation results obtained in pores with native and silanized glass surfaces with those for the bulk liquid. For the present case of high ly viscous MTHF near T-g, the molecular orientation in silanized pores is a lmost identical to that observed in the bulk liquid. This indicates that co nfinement effects remain small and that the interfacial interaction between liquid molecules and the pore wail can dominate and are strongly affected by the surface chemistry. We also demonstrate how solvation dynamics techni ques can be used to measure the dynamics selectively at the interface.