Low-Temperature Surface Forces Apparatus to Determine the Interactions between Ice and Silica Surfaces

We have developed a low-temperature surface forces apparatus (SFA) using a thermoelectric Peltier module inserted below the bottom surface of the lower sample holder, giving easy access to the samples and allowing quick temperature changes. In air, the temperature can be decreased to ca. -20 degrees C. To demonstrate the performance of the apparatus, we measured the interactions between ice and a silica surface at -11.5 +/- 0.5 degrees C. An exponentially decaying repulsion of the decay length, 11.2 +/- 1.0 nm, was observed, and attributed to the electric double layer (EDL) repulsion. The surface potential of the ice was calculated to be -35 mV by fitting the data to the EDL model.