LAUSR

The effect of electric field on nanoconfined liquids is studied in an atomic force microscope. Force spectroscopy experiments were conducted on undecanol and tetradecane on graphite. A strong electric field is applied across the liquid by biasing a gold coated tip up to 3 V across approximately 5 nm or less of liquid confined between the tip and graphite. Oscillatory forces are observed when no electric field is applied, thus indicating molecular ordering of the liquids at the interface. These oscillatory forces are observed far less frequently when a strong electric field is applied across undecanol, whereas only a slight decrease in observation frequency is found in tetradecane. Our interpretation is that trace amounts of water within the liquids is attracted into the tip-sample contact region under high electric field, thus disrupting the molecular layering. This hypothesis is supported by experiments in dried undecanol in which the probability of observing oscillatory forces only decreases slightly up...