Environmental Engineering Reference
In-Depth Information
FiguRe .
Electron. microscopy.. (From. J.. Mansield,. University. of. Michigan.. With.
permission.)
form.clear.images.of.nanomaterials..There.are.two.major.types.of.electron.micros-
copy:.(1).transmission.electron.microscopy.(TEM).and.(2).scanning.electron.micros-
copy.(SEM)..As.a.beam.of.electrons.hits.the.surface.of.a.particle.or.ilm,.electrons.
can.be.delected.off.the.surface.or,.in.collisions.with.atoms.of.the.material,.release.
light,.knock.off.secondary.electrons.from.atoms.in.the.material,.or.cause.the.emis-
sion.of.x-rays..Some.electrons.also.pass.through.the.material,.either.directly.or.with.
some.scattering.due.to.collisions.with.the.particle.atoms.(Figure.5.1).
With.SEM,.emissions.from.the.top.of.a.surface.impacted.by.the.electron.beam.
are.detected.and.measured..A.variety.of.instruments.can.be.used.to.detect.the.back-
scattered.electrons,.secondary.electrons,.x-rays,.or.light.generated.above.the.surface..
Each. detector. adds. its. own. acronym. to. the. analysis. technique. (e.g.,. EDS. [energy.
dispersive. x-ray. spectroscopy],. EDX. [energy. dispersive. x-ray],. and. XEDS. [x-ray.
energy.dispersive.spectroscopy].all.refer.to.x-ray.detection.techniques.that.provide.
structural.or.chemical.composition.information.when.paired.with.SEM)..Auger.elec-
tron. microscopy. or. spectroscopy. (AEM. or. AES),. which. measures. the. energy. of.
