In the work, conventional and dynamic SEM imaging is performed simultaneously. The dynamic part is analysed using the fraction of secondary electron signals synchronous to excitation, which is measured by a lock-in amplifier.

As can be seen in the image, the simulated contrasts in the right column correspond well to the experimental data on the left.

Theoretical benefits

The model, which is based on the time-dependent interaction of the electron beam with the vibrating cantilever, provides information about the relationship between the dynamically excited shape and the topological properties of the so obtained images. It allows the team to distinguish between features that are due to the imaging technique and those that carry relevant information, such as those from nonlinear mechanics.

The explicit solution for the image calculation represents another step towards the analysis of nonlinearity in scanning force microscopy experiments. Such nonlinear behaviour of levers appears during intermittent contact imaging or with multi-frequency excitation, which will be explored in future work.

The researchers presented their results in the journal Nanotechnology.