book of abstracts - IM2NP

A B S T R A C T S THURSDAY, JULY 1 N A N O S E A 2 0 1 0
2 – Abstract
The uniaxial magnetic anisotropy in film materials having large constant of magnetostriction is able to
change its sign and value due to inner stress gradients created by dissipative structures. The correlation of
nanocrystalline film structure with their magnetic characteristics in the process of transition from the
disorder to their regular structure is researched. The other problem considered in this work is a decrease of
saturation magnetization in nanocrystalline films of Co50Pd50 and Fe86Mn13C with tetrahedral closepacked
Frank-Kasper structures.
3 – Conclusion
The data summarized in this paper demonstrated that in nanocrystalline films of metal alloys exists the
possibility of the quantum dots creation in the form of nanocrystallites with Frank-Kasper structure. The
appearance of this quantum dots one can connecting with spectrum of absorption, which shows visible
distinct peaks at wavelength in the area of 1300 nanometers, apparently connecting with exiton optical
transition.
12H30-12H50 Tail effect on trihydroxysilanes dimerization: a DFT study.
1 – Introduction
J.-M. Ducéré1,2, A. Estève1,2, G. Landa1,2, M. Djafari Rouhani1,2, D. Estève1,2 (1
CNRS ; LAAS ; 7 avenue du Colonel Roche, F-31077 Toulouse, France, 2 Université de Toulouse ; UPS, INSA,
INP, ISAE ; LAAS ; F-31077 Toulouse, France). jmducere@laas.fr, aesteve@laas.fr, landa@laas.fr,
djafari@laas.fr, esteve@laas.fr
Organosilanes self-assembled monolayers (SAMs) are widely used for inorganic surfaces modifications in
the field of micro- and nanosystems for to improving the tribological properties, controlling the
hydrophobicity, or introducing chemical functions for further grafting. Obviously, the silane organic tail is
critical for the quality of the so-formed layer. In particular, short alkyl chains and polar groups are known to
lead to highly disordered layers.
In this context, we have already used Density Functional Theory calculations to investigate the hydrolysis
and grafting to silica. Here, we study the influence of the length of terminating alkyl chain and of the
presence of a polar group on trihydroxysilanes dimerization, that can be viewed as the very initial step of the
self-assembly process.
2 – Abstract
In a first time, we consider silanes terminated by two different polar groups: an amine and an ester. We
obtain that the stablest conformation is, in both cases, a head-to-tail one. Indeed, this conformation is favored
because hydrogen-bonds between a silanol and an amine or ester group are stronger than between two
silanols.
In a second time, we investigate alkyl chains of different lengths (C3-C30). Here, the geometry is a
compromise between silanes heads hydrogen-bonds, keeping chains apart, and London interaction, keeping
chains parallel. For chains as short as C6, London interaction dominates but substantially longer chains (C12,
C18) are required for parallel chains being significantly stabler.
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