Workshop

Theory meets Experiment - Organic Molecules on Inorganic Surfaces

Monday 24th June 2013
Time: 09.30 - 17.00
Venue: Chemistry Department, Christopher Ingold Building, UCL.
Workshop: Christopher Ingold XLG1 Chemistry LT.
Refreshments: Nyholm Room.
Contact: TYC Administrator
Tel: +44 (0)20 7679 9950

This focussed one-day workshop has invited talks from leading experimental and theoretical scientists in the area of organic molecules on inorganic surfaces. The main theme is the powerful role that close collaboration between theory and experiment can have, and we welcome contributed talks and posters that exemplify this idea.

The workshop will be an opportunity not only to learn about the latest developments in the field, but also to form new collaborations. There will be plenty of time for informal discussions, and we hope that the workshop will allow us to frame the developments needed to advance the field.

Click here to download the full programme, including talk and poster abstracts.


Invited Speakers:

John Boland (Trinity College Dublin)
Molecule Scattering and Engineered Devices on Silicon

John Polanyi (University of Toronto)
Charge Delocalization Induces Multiple Reaction, Within an Adsorbate Molecule or Along a Chain

Andrew Teplyakov (University of Delaware)
When local chemical functionality requires macroscopic understanding: Multifunctional molecules on functionalized semiconductor surfaces

Saw Wai Hla (Ohio University)
Molecular Superconductors to Molecular Nanomachines

Oliver Warschkow (University of Sydney)
Organic Molecules on the Silicon (001) Surface - Reaction Patterns and Pitfalls


Sponsored by the Institute of Physics
Supported by the Thomas Young Centre
Organisers:  Veronika Brázdová, David R. Bowler, Steven Schofield

 

Registration

Registration for the workshop is done by completing the online form below.

Workshop fee is £25 + fees, which includes refreshments, not including accommodation.

 

Accommodation

Unfortunately, TYC is unable to fund or book accommodation for delegates but there are many hotels close by.  Two hotels, a short walk from UCL, that we recommend include:

The Academy Townhouse - http://www.theacademyhotel.co.uk/

The Tavistock Hotel - http://www.imperialhotels.co.uk/

 

Programme


Borislav Naydenov and John J. Boland (School of Chemistry & Center for Research on Adaptive Nanostructures and Nanodevices (CRANN),  Trinity College Dublin, Ireland.)

In this talk we describe how the presence of atoms and molecules disrupt the electronic connectivity of the dimer rows on Si(100) surface.  We demonstrate that the amplitude and phase of the scattering charge density is specific to the type of adsorbate and sensitive to changes in bonding configuration.  Moreover, we identify the presence of signatures in the scattering that appears to be related to specific loss phenomena.  By position these atoms/molecules it is possible to create single and coupled 1-d quantum wells that behave like artificial molecules.  We map out the spatial and energy distributions of the wavefunctions confined in these wells and show how they couple into the surrounding material. We demonstrate that the wavefunctions in these wells can be effectively gated and we discuss the possibility of developing novel devices whose operation depends on controlling the phase of carrier wave function rather than carrier transport


Kai Huang, Lydie Leung, Tingbin Lim, Zhanyu Ning and John Polanyi (Department of Chemistry, University of Toronto, Toronto, ON, Canada)

Charge Delocalization Induces Multiple Reaction, Within an Adsorbate Molecule or Along a Chain

Abstract: Injecting a single electron by STM into a molecule physisorbed at a surface has commonly been observed to result in dissociative reaction of a single bond of the adsorbate. Here this behaviour will be interpreted by a two-electronic-state model, which accounts for the molecular dynamics. For the case of ortho-diiodobenzene physisorbed on Cu(110), experiments with a single low-energy electron will be shown  to have a strong preference for inducing the reaction of both the C-I bonds in the adsorbate. Theory indicates that this two-bond reaction is due to delocalization of the single added charge. A comparable delocalization of charge along a chain of adsorbed molecules explains, for the first time, the striking observation by Maksymovych, Yates and co-workers (Science, 322, 1664-1667(2008)) that localised electron  deposition on linear chains of dimethyldisulfide (CH3SSCH3), physisorbed on  gold, gives rise to the reaction of  numerous adjacent S-S bonds.


Andrew Teplyakov (University of Delaware)

When local chemical functionality requires macroscopic understanding: Multifunctional molecules on functionalized semiconductor surfaces

Abstract: Recent trends in coupling chemical functionality with desired semiconductor surfaces will be explored in this presentation. We will start with a brief historic perspective on reactivity of multifunctional organic and organometallic compounds on clean group IV semiconductor surfaces and expand this approach to include chemically functionalized and "multifunctional" surfaces and tunable chemical reactivity of surfaces. The complexity of surface structures produced even in reasonably simple chemical processes will be highlighted based predominantly on spectroscopic and microscopic surface analytical techniques. Examples of understanding local surface structures supported by DFT calculations will be given and the role of short- and long-range order on well-defined surfaces will be investigated, posing questions of theoretical interpretation of these results.

 

Saw Wai Hla (Ohio University)

Molecular Superconductors to Molecular Nanomachines

Abstract: Using low temperature scanning tunneling microscopy (STM), spectroscopy, and atom/molecule manipulation schemes, we explore properties of novel molecular materials on surfaces at single atom and molecule level. In this talk, recent results in the area of functional molecules on surfaces studied by STM and tunneling spectroscopy will be presented [1-4]. In spintronic area, we will present engineering of surface assembled molecular Kondo chain [1]. Using a salophen type molecules as basic building blocks, individual molecular chains having 1 to 5 basic units are assembled on a Au(111) surface by means of an Ullmann type ring coupling reaction. These molecular chains reveal isolated Kondo centers at the caged Co atoms. The charge transfer at the molecule metal interface can alter the properties of molecules. We will highlight the effect of an interfacial charge transfer process in the Kondo resonance of TBrPP-Co molecules on Cu(111) surface [2]. Here, the transfer of charge from the surface to the molecule leads to observe the Kondo effect not only at the Co atom but also at the organic ligands indicating that the entire molecule become magnetic including the C atoms. In nanoscale superconductivity area, donor-acceptor type charge transfer based molecular superconducting system will be discussed [3]. Here, the finding of superconductivity in just four pairs of (BETS)2-GaCl4 molecules opens the possibility of investigating superconducting phenomena locally. In molecular machine area, we will present controlled rotation of a stand-alone multi-component molecular motor operated by injecting tunneling electrons from an STM tip [4]. By selectively exciting different rotator arms of these molecular motors, controlled rotations into both, clockwise and counterclockwise directions have been achieved. These innovative experiments are tailored to address several critical issues covering fundamental understanding as well as demonstration of novel atom/molecule based devices on materials surfaces.

[1] A. Dilullo, S. Chang, N. Baadji, K. Clark, J.P. Klöckner, M.H. Prosenc, S. Sanvito, R. Wiesendanger, G. Hoffmann, S.-W. Hla. Molecular Kondo Chain. Nano Lett. 12, 3174-3179 (2012).
[2] U.G.E. Perera, H.J. Kulik, V. Iancu, L.G.G.V.D. da Silva, S.E. Ulloa, N. Marzari, and S.-W. Hla. Spatially Extended Kondo Effect in Magnetic Molecules Induced by Interfacial Charge Transfer. Phys. Rev. Lett. 105, 106601 (2010).
[3] K. Clark, A. Hassanien, S. Khan, K.-F. Braun, H. Tanaka, and S.-W. Hla. Superconductivity in just four pairs of (BETS)2-GaCl4 molecules. Nature Nanotechnology 5, 261-265 (2010).
[4] U.G.E. Perera. F. Ample, H. Kersell, Y. Zhang, G. Vives, J. Echeverria, M. Grisolia, G. Rapenne, C. Joachim, and S.-W. Hla. Controlled clockwise and anticlockwise rotational switching of a molecular motor. Nature Nanotechnology 8, 46-51 (2013).

 

Oliver Warschkow (University of Sydney)

Organic Molecules on the Silicon (001) Surface - Reaction Patterns and Pitfalls

In this talk I will review some of the common reaction patterns of organic molecules on the silicon (001) surface with a focus on examples from our recent work on carbonyls, nitriles, and aromatics. Scanning tunnelling microscopy (STM) provide "snapshot" images of a surface exposed to an organic adsorbate. Drawing on the structural and chemical clues evident in these images, density functional theory (DFT) calculations can identify the species observed and the reaction mechanisms that give rise to them. I will discuss by illustration some of the technical difficulties that are encountered in this work, and the potential to predict organic reactivity on silicon using principles of chemical analogy.


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