Environmental Engineering Reference
In-Depth Information
Structural
Information
Molecular
Information
Scanning Electron
Microscopy (SEM)
Fourier Transform
Infrared Spectroscopy (FTIR)
Energy Dispersive
Spectroscopy (EDS)
Transmission Electron
Microscopy (TEM)
X-Ray Diffraction (XRD)
Thermal Analysis (TA)
Photoacoustic
Spectroscopy (PAS)
Magic Angle Spinning -
Nuclear Magnetic Resonance
(MAS-NMR)
Raman Spectroscopy (RS)
UV-Visible Spectroscopy
(UV-VS)
BULK
Mercury Intrusion
Porosimeurtry (MIP)
Atomic Force Microscopy/
Scanning Tunneling
Microscopy
(AFMSTM)
Surface
(1-50 A)
Etc.
Etc.
Surface
Information
X-ray Photoelectron
Spectroscopy (XPS)
Auger Electron
Spectroscopy (AES)
Ion Scattering
Spectroscopy (ISS)
Secondary Ion Mass
Spectrometry (SIMS)
Particle Desorption
Mass Spectrometry
(POMS)
Etc.
FIGURE 9.1
Summary of techniques used for characterization of S/S waste forms.
41
sections (30-μm thickness), however, need to be prepared. Observations at higher
magnifications require electron microscopes. SEM, which allows much higher depth
of field than transmission microscopes, has improved our understanding of the
microstructure of waste forms at magnifications ranging from a few tens to many
tens of thousands. For insulators, SEMs usually require that the specimens have a
conductive coating and need to be placed in an evacuated chamber. This process
may affect the microstructure of moisture-rich specimens. This is particularly true
for clay minerals, such as bentonite, which absorb water many times their original
volume. Transmission electron microscopes (TEMs) operate very much like trans-
mission optical microscopes, but because electrons are used for observations, instead
of light, the resolution is much higher. Magnifications of several hundreds of thou-
sands can be attained with a TEM.
Many attachments are available with the SEM and TEM, which provide infor-
mation complementary to the microstructure. For example, an EDX spectrometer
can be attached to the SEM and the local chemical composition can be analyzed
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