LOCAL ELASTICITY AND LUBRICATION MEASUREMENTS USING ATOMIC-FORCE AND FRICTION FORCE MICROSCOPY AT ULTRASONIC FREQUENCIES

We have modified an Atomic Force Microscope (AFM) that allows the dete ction of cantilever bending as well as torsional vibrations at ultraso nic frequencies, Oscillating either probe tip or sample vertically mod ulates the normal force about the setpoint farce, acting between tip a nd sample, When the tip contacts the sample, the surface resists the o scillation and deformation of the sample is dependent on the local sti ffness or elasticity. For a constant normal force, a soft area deforms more than a hard area and thus the cantilever deflection is less over a soft area, The variations in cantilever vertical oscillation is a m easure of relative elasticity of the sample, Elasticity maps with a la teral resolution of better than 100 nm have been taken on alumina-base d ceramic composite, and on two metal particle (MP) recording tapes, B y vibrating the sample laterally, the shear forces are modulated, Dete cting and analyzing the cantilever torsional behavior we are able to c haracterize friction and viscosity of thin films used for lubrication of magnetic disks.