Experimental observation of interfacial slippage at the boundary of molecularly thin films with gold substrates

Abstract

Physisorbed monolayers and multilayers adsorbed on the surface electrodes of a resonating quartz microbalance produce shifts in both the frequency and amplitude of the oscillator. The shift in frequency results from mass loading and the shift in amplitude results from film dissipation effects. We have measured these shifts for molecularly thin nitrogen and krypton films and observe levels of film dissipation which cannot be adequately accounted for within the context of the ‘‘no-slip’’ boundary condition of hydrodynamics. The data provide strong evidence that the excess dissipation arises from slippage at the film substrate interface since the film thicknesses studied are negligible compared to the viscous penetration depths of the respective materials.