Dr Timothy Petersen

Dr Timothy PetersenResearch Fellow

Bachelor of Science (Applied Physics), RMIT University, 2000.
PhD (Applied Physics), RMIT University, 2004.
Phone +61 (3) 9905 9765
Fax +61 (3) 9905 3637

Email: Timothy.Petersen@monash.edu

principle curvature of an aluminium atom probe lens

Figure: principle curvature of an aluminium atom probe lens, derived from the 1st and 2nd fundamental forms, which were computed from an electron tomogram reconstructed from 161 bright field images over +/- 80 degrees, using the 'surface-tangent' algorithm. Prior to the differential geometry calculations, the undistorted 'missing wedge' in the 3D point cloud was filled in by computing roughly 1000 Taylor series to estimate the slow angular variation of the aluminium tip about the tip axis, which was aligned with the electron microscope tilt axis.

Research interests

I regard myself as a physicist working in the area of electron microscopy. Most of my research to date has centred on improving experimental measurements through computational and theoretical algorithm development. For quantitative experimental data interpretation, I have also developed modelling approaches utilising computational physics. Most recently, I have taken up the challenge of experimentally measuring scalar and vector electro-magnetic fields using a combination of electron tomography and phase retrieval.

Research topics of interest:

  • Radial distribution functions (RDFs) of disordered solids
  • Energy filtered electron diffraction measurements of RDFs and associated software development
  • Development of Hybrid Reverse Monte Carlo based modelling of disordered microstructure
  • Theoretical modelling of Carbon based fullerenes and multi-layered curved nano-surfaces using advanced surface diffusion algorithms
  • In-line electron holography using phase retrieval based upon the transport of intensity equation
  • Theoretical approaches to electron phase retrieval in the transmission electron microscope (TEM)
  • Electron tomography, 3D morphology measurement and algorithm development for TEM
  • Atom probe tomography and reconstruction
  • Ultra-thin complex-oxide hetero-structures of ferro-electric and ferro-magnetic tunnel junctions for spintronics applications
  • Synthesis and TEM characterisation of nano-particles through sublimation in ultra-high vacuums
  • Electron tomography of electro-magnetic fields

Selected publications

"An electron tomography algorithm for reconstructing 3D morphology using surface tangents of projected scattering interfaces" , T. C. Petersen and S. P. Ringer, Comp. Phys. Comm., 181, 676 (2010).

"Electron tomography using a geometric surface-tangent algorithm: Application to atom probe specimen morphology", T. C. Petersen, S. P. Ringer, J. App. Phys, 105, 103518 (2009).

"Influence of field evaporation on Radial Distribution Functions in Atom Probe Tomography", D. Haley D, T. Petersen, G. Barton and S. P. Ringer, Philosophical Magazine, 89, 925-943 (2009)

"Plasmon resonances and electron phase shifts near Au nanospheres", T. C. Petersen, M. Bosman, V. J. Keast and G. Anstis, Appl. Phys. Lett. 93, 101909 (2008).

"Quantitative TEM based phase retrieval of MgO nano-cubes using the transport of intensity equation", T C. Petersen, V. J. Keast, and D. M. Paganin, Ultramicroscopy, 108, 805-815 (2008).