Scanning Electron Microscopy and X-Ray Microanalysis

355 21

EDS

detector

window

Collimator &

electron trap

Final

lens

Chamber

wall

BSE

Aperture

scattering

Conventional SEM,

pathological scattering

Spectrum from high purity flat

scattering target, e.g., C, Ta,

surrounded by different materials,

e.g., Ag-epoxy, Ti, Al

Green =

Extent of

specimen

X-ray sources

NOT excluded

by collimator

Multi-material “flat scatter” test specimen

. Fig. 21.15 Schematic
diagram of the “in-hole”
configuration with a pure
element target placed at the
center of a multi-material target

Carbon

E 0 = 20 keV

12% deadtime, 112 kHz

500s (12,500 nA-s)

0.1 – 20 keV integral

= 56 million counts

Ag

0 1.0 2.0 3.0 4.0 5.0

Photon energy (keV)

6.07.0 8.09.0

FullamplainC_20kV25nAME

112kHz12DT500s10kx_02-09-09

10.0

Ti

Si K-

edge

C K

C K + C K

Counts

. Fig. 21.16 Measurement of
high purity C surrounded by Ag
(doped epoxy) and titanium; no
significant signals for Ag or Ti are
observed

21.4 · Pathological Electron Scattering Can Produce “Trace” Contributions to EDS Spectra