Theory of atomic-scale manipulation
in complex molecular systems in STM:
Chemistry in the high electrical field
V.S. Gurin*
Belarusian State University
This is an abstract
for a talk to be given at the
Fifth
Foresight Conference on Molecular Nanotechnology.
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The
author regrets that unexpected events have forced him
to cancel his attendance and this presentation. |
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A number of experimental studies of local modification of
solids in STM show a variety of processes responsible for this
phenomenon. However, there is no consistent theory that could
explain all transformations in solid surface observed in the
experiments. The very different chemical nature of materials
subjected to STM-stimulated modification and troubles with usage
of conventional analytical methods due to small amount of matter
in the reactions do not give possibility to elaborate detailed
mechanisms (sequence of chemical reactions, transition states,
products, etc.). We deal with a theoretical approach to this
problem based on quantum-chemical analysis (with ab-initio
methods) of the states of a 'nanometer-scale reaction system'.
This system consist of a cluster from several atoms and STM tip
located at a short distance from it. The high electrical field
near the tip has a remarkable effect upon the molecular structure
simulated by the finite cluster. The field contributes to the
chemical reactivity of molecules and clusters, and some unusual
processes may take place and can be used for directed
construction on solid surface in nanotechnology.
The approach is applied for some certain systems which are of
interest from the experimental point of view (grafite, silver
surface, palladium acetate film). Quantum chemical calculations
of electronic structure and energetical characteristics of the
surface clusters under the STM tip field show pathways of the
reconstruction, chemical bond breaking, electronic excitation.
Formation of new species being intermediate products of
STM-stimulated transformation is proposed.
*Corresponding Address:
Valerij S. Gurin, Physico-Chemical Research Institute, Belarusian
State University, Leningradskaja str., 14, 220080, Minsk,
BELARUS; fax: 375-172-264696, e-mail: [email protected]
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