Dmitrii Razinkov Kristín Vilbergsdóttir Selma Rut Sófusdóttir The JEOL JXA8230 electron microprobe Mechanism of the instrument Electrons emitted from the electron source are accelerated at a certain accelerating voltage and collimated through electron lenses When this electron beam hit ID: 789770
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Slide1
Electron microscope
Arnór Freyr Sævarsson
Dmitrii Razinkov
Kristín Vilbergsdóttir
Selma Rut Sófusdóttir
Slide2The JEOL JXA-8230 electron microprobe
Slide3Mechanism of the instrument
Electrons emitted from the electron source are accelerated at a certain accelerating voltage and collimated through electron lenses. When this electron beam hits a specimen, X-rays are generated from the specimen. By dispersing this X-ray using a dispersive element, the composition of the specimen can be examined. This type of spectrometer is called a wavelength dispersive X-ray spectrometer (WDS)
Slide4When accelerated electrons hit a specimen, in addition to the X-rays, particles and electromagnetic waves carrying various kinds of information are emitted. With EPMA, signals such as the characteristic-X-rays, secondary electrons, backscattered electrons, are detected by the appropriate detectors and that information is utilized to find the area of interest on a specimen, and for analysis.
Slide5Uses of the instrument
The only instrument of its kind in Iceland;
Primarily used for accurate quantitative chemical analyses of solid material and high-resolution imaging;
Disciplines that can use EPMA : mineralogy, petrology, chemistry, nanotechnology, archeology…;
Particles down to 10 μ
m size or even smaller can be analyzed
Industrial enterprises can use electron microprobe for quality control in the production of alloys and semiconductors
Slide6Rafeindasmásjá
Er smásjá sem notar rafeindageisla til að útbúa mynd af sýni.
Skannar yfirborð sýnisins og rafeindirnar víxlverka á atómin í sýninu og endurkasta merki sem gefur mynd af yfirborði sýnisins.
Endurkastið kemur frá:
Backscattered rafeindum
Secondary rafeindum
Auger rafeindum
X-ray ljómun
Slide7Backscattered rafeind:
er háorku rafeind sem endurkastast án þess að hægja á sér.
Secondary rafeind:
er lágorku rafeind, yfirleitt af innsta hveli þar sem rafeind úr geislanum hefur rekið hana út eftir árekstur.
Slide8Auger rafeind:
Er rafeind af millihveli sem fær orku frá ytri rafeind sem fer inn á innra hveli eftir að secondary rafeindin fer, þannig hún fer í burtu.
X-ray ljómun:
Er orkan sem losnar þegar rafeind af ytra hveli fer í opið þar sem secondary rafeindin var.
Slide9Rafeindasmásjáin í notkun
Þungt málmgrýti fannst á Íslandi sem hugsanlega væri úr loftsteini.
Sneiðmynd af grýtinu er útbúin og sett í rafeindasmásjánna.
Slide10Nærmynd
Hér eru sýndar tvær aðferðir til að skoða yfirborð sýnis:
COMPO . Notar back-scattered electrons þar sem dekkri yfirborð eru léttari.
SEI (Secondary electron imaging). Einungis yfirborð sést.
Þrír fasar sjáanlegir:
Ljós
Mið
Dökkur
Einnig sést gasfasi.
Gasfasar finnast ekki í loftsteinum.
Slide11Með EPMA er hægt að greina efnasamsetningu mismunandi fasa. Notar x-rays.
Hér er tekið fasa 1 eða ljósa fasann til dæmis.
Frumefni atom %
O 52,5
Al 0,7
Mn 4
Fe 42,6
Efnaformúlan 2Fe3O
Slide12