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Structural and compositional characterization of nano-film systems using a new technology  of High Resolution Impedance Spectroscopy

Michal Baudouin 

Agricultural University, Dep. of Chemistry, Nowoursynowska 159c, Warszawa 02-776, Poland


The construction and study of bio-molecular interfaces on gold, silica and silicon substrates and electrodes has attracted a great deal of attention, both because of a basic interest in the physical properties of low dimensional structures per sé and because such nano structures have many possible device applications. The latter include molecular sensors, nano-electronic devices, memories, displays etc.  Molecular self-assembly is a convenient tool for producing novel nano-architectures at the solid interface and the functionalisation of the surface by attachment of, for instance, enzymes or self-assembly of synthetic DNA.

 Development of the methodologies for producing biomimetic and bio-functionalised surfaces requires detailed characterization of the surface nano-structures.  A number of physical and physico-chemical techniques can be utilized for this, including neutron and X-ray reflectometry, atomic force microscopy (AFM), scanning tunneling microscopy (STM). Electron microscopy (EM), elipsometry and X-ray photoelectron spectroscopy (XPS).  These techniques are all extremely useful but are often cumbersome to apply to these particular studies and/or require a large equipment infrastructure not always readily accessible.

 We have developed a laboratory-bench instrument based on a novel, very high resolution, impedance spectroscopy technique that provides molecular and in some cases, atomic, scale resolution of the layered architecture of two dimensional nano- structures.  In order to achieve unequivocal analysis of these structures at this level of resolution, it is necessary to obtain very high precision measurements of both the phase and magnitude of the impedance over a wide range of frequencies. The impedance technology developed in our laboratory provides resolution of 0.001 degrees in phase and 0.002% in impedance magnitude.  This has allowed the detailed characterization of, for example, organic films covalently linked to silicon with a spatial resolution of a single carbon-carbon bond. Results are presented of the application of the technique to a variety of synthetic biomimetic surfaces of importance in the development of biosensing and biocompatible surfaces.


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Presentation: Poster at Nanotechnologia PL, by Michal Baudouin
See On-line Journal of Nanotechnologia PL

Submitted: 2010-07-20 15:49
Revised:   2010-07-20 15:51