Page 119 - Environmental Nanotechnology Applications and Impacts of Nanomaterials

Chapter
4

Methods for Structural and

Chemical Characterization

of Nanomaterials

Jérôme Rose CNRS, University of Aix-Marseille, Aix-en-Provence, France
Antoine Thill CEA, Saclay, France
Jonathan Brant Duke University, Durham, North Carolina, USA

Introduction
In this chapter, we survey several methods for characterizing physical-
chemical properties of nanoparticles. Among these properties are particle
size, charge, structure, shape, and chemical composition. Particle size
can influence an array of material properties and is therefore of concern
when studying nanoparticles. For example, the crystal properties of the
material such as the lattice symmetry and cell parameters may change
with size due to changes in surface free energy [see, for example, Zhang
and Banfield, 1998]. This is particularly true for particles where the
number of atoms at the surface represents a significant fraction of the total
number of atoms (e.g., below 10 to 20 nm). Size may also affect the elec-
tronic properties of the materials due to the confinement of electrons,
commonly discussed in terms of the quantum size effect, and the
existence of discrete electronic states that give rise to properties such
as the size-dependent fluorescence of CdS and CdSe nanoparticles or the
electrical properties of carbon nanotubes.
The surface properties of nanomaterials play an important role in
determining nanoparticle toxicity. The toxicity of CdS and CdSe
nanoparticles, for instance, is completely controlled by their surface
coating. The intracellular oxidation of bare CdSe nanoparticles results

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