Isotope effect in the interaction between gas-phase isotopologues and polymer-coated porous silicon over silicon microcantilevers

A kinetic isotope effect is observed in the guest-induced bending curves of poly-4-vinylpyridine-coated microcantilevers. Protiated (nondeuterated) and deuterated isotopologues of ethanol, water, and acetone exhibit a clear difference in their time dependent bending response patterns. While most protiated species exhibit Langmuir-type absorption bending curves, the bending curves of deuterated species are characterized by a clear overshoot. Time-dependent Fourier-transform infrared measurements provide further insight into the interrelation between molecular level interactions and macroscopic mechanical bending. A model is suggested to interpret these observations.