LATERAL STIFFNESS - A NEW NANOMECHANICAL MEASUREMENT FOR THE DETERMINATION OF SHEAR STRENGTHS WITH FRICTION FORCE MICROSCOPY

We present a technique to measure the lateral stiffness of the nanomet er-sized contact formed between a friction force microscope tip and a sample surface. Since the lateral stiffness of an elastic contact is p roportional to the contact radius, this measurement can be used to stu dy the relationship between friction, load, and contact area. As an ex ample, we measure the lateral stiffness of the contact between a silic on nitride tip and muscovite mica in a humid atmosphere (55% relative humidity) as a function of load. Comparison with friction measurements confirms that friction is proportional to contact area and allows det ermination of the shear strength. (C) 1997 American Institute of Physi cs.