Oct 26, 2010
Frequency-modulated SPM quantifies energy dissipation
In addition to answering numerous fundamental physics and materials science questions, measuring energy dissipation on the nanoscale is the key to understanding important energy transformation and loss mechanisms that ultimately underpin the efficiency of energy storage and information technologies.
Despite a number of attempts, quantitative measurement of energy dissipation in scanning probe microscopy (SPM) has remained elusive, poorly reproducible and non-quantitative. Now, scientists at Asylum Research corporation and Oak Ridge National Laboratory (ORNL) have demonstrated that this irreproducibility plaguing the field for the last two decades is due to minute fluctuations of the transfer function of the system, i.e. the frequency-dependent relationship between the voltage-driving acoustic piezo and effective force. These errors, while small for conservative forces, dominate the dissipative contrast.
The study was an offshoot of recent work at ORNL and Asylum Research developing multi-frequency SPM techniques such as band excitation and dual amplitude resonant tracking – control techniques that replace traditional sinusoidal excitation with more complex waveforms that allow more quantitative probing of dissipative interactions in all ambient and liquid SPM modes.
More information can be found in the journal Nanotechnology.
About the author
Roger Proksch is president of Asylum Research. Sergei Kalinin is a staff scientist at ORNL's Center for Nanophase Materials Sciences.