Friction STM FrictionForce Oxidation MolybdenumDisulfide bias_mode LiquidImaging semifluorinated alkane Hafnia GaP Sapphire Metal HACrystal ElectroDeposition NTU LiquidCrystal GaAs Mfm amplitude_modulation nanomechanical Protein Vanadate Aggregated_molecules Composition Dental plastic Melt pulsed_laser_deposition Monisha Litho P3HT Led Iron HydroGel fluorocarbon