April 01, 2010

Online Interview with Philip Moriarty Who is Experimenting to Validate or Disprove the Computational Work of Freitas and Merkle Molecular Tooltips

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There is a two part interview with Philip Moriarty at 10minus9 blog

I work in a variety of fields in nanoscience including self-assembly and pattern formation, fullerenes, synchrotron-based spectroscopy, and charge transport in nanoparticle assemblies, but my primary project at the moment focuses on an area which what at least one funding agency in the UK has termed “extreme nanotechnology”. The bulk of my funding is related to the development of atomic manipulation protocols on semiconductor and insulator surfaces (silicon and diamond). The aim is to explore to what extent it’s possible to fabricate nanostructures, atom-by-atom and automatically (i.e. under computer control), using scanning probes. A key aspect of this work is to move away from 2D manipulation (i.e. atom sliding/pushing/pulling) and to attempt fabrication of 3D structures. This is immensely challenging because it entails gaining fine control of an element of a scanning probe microscope which, although integral to its operation, is still generally a key unknown: the tip. Somewhat controversially, the project examines the extent to which Eric Drexler’s ideas regarding force-driven chemical reactions at the atomic/molecular scale (mechanosynthesis) can be realised and was inspired by a lengthy debate I had on the subject of Drexlarian nanotechnology with Chris Phoenix at the Centre for Responsible Nanotechnology a number of years ago.

Part 2 of the Philip Moriarty Interview

The Philip Moriarty five year project for experimentally work on mechanosynthesis was discussed here in August 2008

Finally experiments have been funded to test the viability of diamond mechanosynthesis as described in detail by Robert Freitas and Ralph Merkle. This is a major step towards achieving the long held vision of molecular nanotechnology as envisioned by Eric Drexler.

Moriarty is interested in testing the viability of positionally-controlled atom-by-atom fabrication of diamondoid materials as described in the Robert Freitas-Ralph Merkle minimal toolset theory paper. Moriarty’s efforts will be the first time that specific predictions of DFT in the area of mechanosynthesis will be rigorously tested by experiment. His work also directly addresses the requirement for “proof of principle” mechanosynthesis experiments requested in the 2006 National Nanotechnology Initiative (NNI) review, in the 2007 Battelle/Foresight nanotechnology roadmap, and by EPSRC’s Strategic Advisor for Nanotechnology, Richard Jones (Physics, Sheffield University, U.K.).

Robert Freitas and Ralph Merkle are the leading researchers of the direct to diamondoid pathway to molecular manufacturing

University of Nottingham Nanoscience Group Homepage

Latest Publications of the Nottingham Nanoscience Group

X-ray absorption and photoemission spectroscopy of zinc protoporphyrin adsorbed on rutile TiO2(110) prepared by in situ electrospray deposition
A. Rienzo, L. C. Mayor, G. Magnano, C. J. Satterley, E. Ataman, J. Schnadt, K. Schulte and J. N. O'Shea
J. Chem. Phys. 132, 084703 (2010)

Supramolecular Assemblies Formed on an Epitaxial Graphene Superstructure
A. J. Pollard, E. W. Perkins, N. A. Smith, A. Saywell, G. Goretzki, A. G. Phillips, S. P. Argent, H. Sachdev, F. Müller, S. Hüfner, S. Gsell, M. Fischer, M. Schreck, J. Osterwalder, T. Greber, S. Berner, N. R. Champness and P. H. Beton
Angew. Chem. Int. Ed., 49, 1794 –1799 (2010)

Theoretical and experimental comparison of SnPc, PbPc, and CoPc adsorption on Ag(111)
J. D. Baran, J. A. Larsson, R. A. J. Woolley, Yan Cong, P. J. Moriarty, A. A. Cafolla, K. Schulte and V. R. Dhanak
Phys. Rev. B, 81, 075413 (2010)

A combination of normal-incidence x-ray standing-wave (NIXSW) spectroscopy, x-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM), and density-functional theory (DFT) has been used to investigate the interaction of a number of phthalocyanine molecules (specifically, SnPc, PbPc, and CoPc) with the Ag(111) surface. The metal-surface distances predicted by the DFT calculations for SnPc/Ag(111) (2.48 Å) and CoPc/Ag(111) (2.88 Å) are in good agreement with our NIXSW experimental results for these systems (2.31±0.09 and 2.90±0.05 Å, respectively). Good agreement is also found between calculated partial density-of-states plots and STM images of CoPc on Ag(111). Although the DFT and Pb 4f NIXSW results for the Pb-Ag(111) distance are similarly in apparently good agreement, the Pb 4f core-level data suggest that a chemical reaction between PbPc and Ag(111) occurs due to the annealing procedure used in our experiments and that the similarity of the DFT and Pb 4f NIXSW values for the Pb-Ag(111) distance is likely to be fortuitous. We interpret the Pb 4f XPS data as indicating that the Pb atom can detach from the PbPc molecule when it is adsorbed in the “Pb-down” position, leading to the formation of a Pb-Ag alloy and the concomitant reduction in Pb from a Pb2+ state (in bulklike films of PbPc) to Pb0. In contrast to SnPc, neither PbPc nor CoPc forms a well-ordered monolayer on Ag(111) via the deposition and annealing procedures we have used. Our DFT calculations show that each of the phthalocyanine molecules donate charge to the silver surface, and that back donation from Ag to the metal atom (Co, Sn, or Pb) is only significant for CoPc

Above-barrier surface electron resonances induced by a molecular network
R. Stiufiuc, L. M. A. Perdigão, B. Grandidier, D. Deresmes, G. Allan, C. Delerue, D. Stiévenard, P. H. Beton, S. C. Erwin, M. Sassi, V. Oison and J. M. Debierre
Phys. Rev. B 81, 045421 (2010)

Patterns and Pathways in Nanoparticle Self-Organisation
M. O. Blunt, A. Stannard, E. Pauliac-Vaujour, C. P. Martin, I. Vancea, M. Šuvakov, U. Thiele, B. Tadic and P. Moriarty
in the Oxford Handbook of Nanoscience and Technology (Volume 1: Basic Aspects),
editors: A. V. Narlikar and Y. Y. Fu, ISBN: 978-0-19-953304-6 (Oxford University Press, 2010)

Their positional assembly page (may not be up to date)

Robert Freitas website
Ralph Merkle website

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