Part of the Oxford Instruments Group
Expand

AM-FM Viscoelastic Mapping Mode

AM-FM Viscoelastic Mapping Mode is a tapping mode-based technique that measures both the surface topography and viscoelastic mechanical properties. It is particularly useful for analyzing polymer blends. AM-FM Viscoelastic Mapping Mode is exclusive to Asylum Research.

What does it measure? AM-FM mode quantitatively maps both topography and viscoelastic properties, including the elastic storage modulus (E’) and viscous loss tangent (tan δ), which can be related to the loss modulus (E’’).
How does it work?

AM-FM is based on conventional tapping mode. AM-FM excites the fundamental flexural resonance of the cantilever and operates in AM (amplitude modulation) mode at that frequency, mapping surface topography. Unlike tapping mode, the cantilever is also driven at a higher resonance frequency and operated in FM (frequency modulation) mode.

The phase response at the fundamental can be related to the viscous properties (loss tangent) of the material. The frequency shift at the higher frequency can be related to stiffness variations across the sample. These data are used to calculate the quantitative elastic storage modulus (E’) and viscous loss tangent (tan δ).

AM-FM mode offers several advantages over other nanomechanical modes. It is very gentle and does not damage samples. This permits ultra-high resolution. It can also make measurements very rapidly using fast scanning tapping mode technology. Finally, it can provide useful information about materials like polymers that have a strong viscous response.

What are its applications? AM-FM is useful for characterizing polymer thin films, multilayer polymer films, and polymer blends. These blends typically exhibit spatial variations in both elastic and viscous properties. Additionally, it can be used on higher modulus materials, like metals.