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QIT-SSL Seminar Series 2007 No.2
Date: 21 May (Monday), 2007
Time: 2:00am-3:00pm
Venue: Physics Resource Room (Blk S13-02-16)
Speaker: Dr.Chen Wei
Title: Assembling linear fullerene arrays for quantum information processing
Abstract:
Creation of well-ordered functional molecular arrays at the nanometer scale is one of the key issues in the development for future molecular- or nano-electronic devices, solid-state quantum computation, single-electron devices, and biosensors. In particular, in proposed fullerene-based quantum computers, two-dimensional fullerene arrays with long range ordering are the ideal building units for the fault-tolerant quantum computers. By manipulating the subtle balance between intermolecular, intramolecular and interfacial interactions, we demonstrate the formation of various well-ordered C 60 superstructures with tunable periodicity and symmetry, including C 60 dot arrays, C 60 -rail arrays and C 60 -pair arrays on a-sexithiophene (6T) bilayer on Ag(111), single-chain and double-chain C 60 arrays on 6T monolayer on Ag(111), “Zigzag” C 60 arrays on 6T monolayer on HOPG, C 60 supergrating and square-nanomesh on p -sexiphenyl (6P) bilayer on Ag(111). It is found that that the formation of the tunable C 60 molecular arrays arises from the delicate balance between the homo-intermolecular (C 60 -C 60 and 6T-6T or 6P-6P, van-der-Waals forces), hetero-intermolecular (C 60 -6T or C 60 -6P, charge transfer) and molecule-substrate [C 60 -Ag(111) and 6T-Ag(111), 6T-HOPG or 6P-Ag(111)] interfacial interactions under different experimental conditions, which can be simply adjusted by choosing appropriate C 60 and 6T or 6P coverages and post annealing temperature. Our results suggest that controlling the intermixed phases of binary or multicomponent molecular systems represents a simple and effective method for the construction of highly ordered functional molecular nanostructure arrays , and offers a versatile route towards the fabrication of novel molecular interconnects and devices. In particular, it could be a possible nanofabrication route towards a fullerene-based quantum computer. |
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SSL Seminar Series 2007 No.1
Date: 26 March (Monday), 2007
Time: 4:00am-5:00pm
Venue: Physics Conference Room (Blk S13 # M-11/12)
Speaker: Dr.Yasuyuki Yokota
Title: Electrochemical STM Investigations of Strong Intermolecular Electronic Coupling within a TTF Island
Abstract:
From the viewpoint of molecular electronics, we have studied the structural and electronic properties of TTF derivatives on gold substrate. In this seminar, I report the electrochemical STM (EC-STM) studies of tetrathiafulvalene (TTF) islands embedded in n -decanethiol SAMs on Au(111). EC-STM measurements of TTF islands of varied sizes at various potentials were performed in 0.05 M HClO 4 solution. From the cyclic voltammetry of self-assembled monolayers, the electronic states of TTF moieties in each STM images were characterized. It was found that the larger the size of the large islands, the higher the apparent height in the STM images, although the physical height of the islands can be assumed to be same. We think that the effective electron transfer between TTF moieties leads to increase of electron-transfer passes due to the strong intermolecular elecronic coupling. The results of ferrocene islands will be also reported to discuss the case of weak intermolecular ineractions.
About speaker:
Dr. Yasuyuki Yokota received his Ph.D. in chemistry from the Tokyo Institute of Technology (TIT) in 2007. He was a Ph.D. candidate working under the direction of Prof. Toshiaki Enoki and Prof. Ken-ichi Fukui at TIT, and a junior research associate working under the direction of Prof. Masahiko Hara at RIKEN. His thesis focuses on electrochemically-controlled molecular devices. His research interests involve the study of surface electrochemistry and electrochemical nanotechnology.
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