On a viscoelastic material, regions of greater loss modulus dampen the cantilever modulation more substantially, 1-4 i.e. dissipate more strain energy. Enhanced viscoelastic dissipation also translates into greater friction under sliding contact. Variations in storage modulus and adhesion on a viscoelastic material may further complicate frictional response. A systematic examination of competing mechanisms necessitates multiple, complementary imaging modes.
Brighter regions correspond to higher surface elevation or frictional force.
This response also is conducive to modeling the dynamics of intermittent contact. Brighter regions correspond to higher amplitude or phase. The phase image relates to the dissipative characteristics of the material.