EMIT: Electromagnetic interactions in tunneling

• Forschungsstelle: EU FRP
• Projektnummer: 97.0459
• Projekttitel Englisch: EMIT: Electromagnetic interactions in tunneling

Schlüsselwörter (Englisch)

Scanning tunneling microscope; electromagnetic interactions; photons; light emission; electron tunneling; metals; molecules; fluorescence; nanometer; optical spectroscopy; photonics

Alternative Projektnummern (Englisch)

EU project number: FMRXCT980198

Forschungsprogramme (Englisch)

EU-programme: 4. Frame Research Programme - 10.1 Stimulation of training and mobility

Kurzbeschreibung (Englisch)

See abstract

Partner und Internationale Organisationen (Englisch)

Katholieke Universiteit, Nijmegen (NL); Rheinisch-Festfälische Technische Hochschule, Aachen (D); University of Dublin, Trinity College (UK); Université de la Méditerranée (F); Chalmers University of Technology (S)

Abstract (Englisch)

The goal of the EMIT project is the acquisition and understanding of photonic information on the nano-scale from a variety of samples of basic physical importance and of potential future industrial relevance.
There are several features of the project work that we highlight this year.
The first is some solid progress in the explanation of the spectral output from STM. Hitherto in the literature, various spectral shapes have been reported, some with a single broad peak, others with a double peak and so on, even for simple junctions e.g. gold tip on a gold sample surface. The role of tip shape in determining the spectral output has now been elucidated in combined theoretical and experimental work emanating from Göteborg and Kiel respectively. Much of the detail of the picture still needs to be filled in, but the main features are clear and there is now the real prospect of theory driven investigations.
The second highlight is the progress in spectroscopy across the network. Specifically, it has now been demonstrated (in Nijmegen) that, for an air operating STM system, there is definite spectral information retrievable from a monolayer of dye molecules on the surface of a Ag sample. A further significant development (at Kiel) is that, under UHV conditions, a complete spectrum of the light output can be taken at each point in the topographic image; the
system thus offers huge spectroscopic potential.

In Zurich a variety of molecular systems are being investigated to establish links between molecular structure, substrate molecule interactions and light emission characteristics. The principal features being explored are the roles of electronic coupling of the molecule to the substrate and the role of fluorescent groups within the molecule. The results indicate that decoupling of fluorescent groups from the substrate tends to favor strong light emission. In particular, the use of t-butyl binding groups appears to be useful for enhanced light emission. These groups are photonically inactive and can be attached to poly-aromatic molecular systems. Spectral characteristics of the light and observed vibrational fine structure of the molecules have also been investigated.
Furthermore we investigated the first generation of a new mechanical receptor, 'mechanoreceptor', possessing a flexible container group. Via STM investigations in atomic resolution we observe that the SAM of one of these mechanoreceptors forms well-ordered monolayers in vase confirmation at room temperature. These results suggest that these receptors are viable candidates for a new class of molecular machines. Additionally, these systems show exciting electro-optical properties, which are under further investigations.

Datenbankreferenzen (Englisch)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 97.0459