Final Technical Report

Efthimios Kaxiras

关键词: ABSORPTION;    CARBON;    COATINGS;    DESIGN;    DNA;    DNA SEQUENCING;    DYES;    MOLECULAR STRUCTURE;    NANOSTRUCTURES;    NANOTUBES;    STABILITY;    SUBSTRATES;    TITANIUM;    TRANSISTORS Multiscale modeling;    theory of surfaces;    nanostructured materials;   

DOI  :  10.2172/946728
RP-ID  :  DOE/ER/46226-1
PID  :  OSTI ID: 946728
Others  :  TRN: US201006%%838

美国|英语

来源: SciTech Connect

【 摘 要 】

This research consisted of a theoretical investigation of the properties of surface-based nanostructures, having as a main goal the deeper understanding of the atomic-scale mechanisms responsible for the formation and stability of such structures. This understanding will lead to the design of improved systems for applications in diverse areas such as novel electronic devices, sensors, field-effect transistors, substrates with enhanced hydro-phobic (water repelling) or hydro-philic (water absorbing) behavior for coatings of various surfaces used in bioengineering, flexible displays, organic photovoltaics, etc. The research consisted of developing new theoretical methodologies and applying them to a wide range of interesting physical systems. Highlights of the new methodologies include techniques for bridging different scales, from the quantum-mechanical electronic level to the meso-scopic level of large molecular structures such as DNA, carbon nanotubes and two-dimensional assemblies of organic molecules. These methodologies were successfully applied to investigate interactions between systems that are large on the atomic scale (reaching the scale of microns in length or milliseconds in time), but still incorporating all the essential elements of the atomic-scale structure. While the research performed here did not address applications directly, the implications of its finding are important in guiding experimental searches and in coming up with novel solutions to important problems. In this sense, the results of this work can be incorporated in the design of many useful applications. Specifically, in addition to elucidating important physical principles on how nano-structures are stabilized on surfaces, we have used our theoretical investigations to make predictions for useful applications in the following fields: a) we proposed new types of nanotubes that can overcome the limitations of the carbon nanotubes whose properties depend sensitively on the structure which cannot be controlled experimentally; b) we showed how carbon nanotubes can be employed in optical determination of the DNA base sequence, an exciting application for ultra-fast DNA sequencing; c) we proposed a nano-structure (titanium dioxide nano-wire) based design for organic photovoltaics using natural dyes, and showed that it will be an efficient system for the absorption of light and the charge transfer from the dye to the wire.