Scanning Electron Microscopy and X-Ray Microanalysis

447 25

DTSA-II Monte Carlo simulation

40Cu-60Au

E 0 = 20 keV

4 mm gas path length

High_vacum_40Cu-60Au_20keV

High_vacum_40Cu-60Au_20keV

53Pa_H2O_40Cu-60Au_20keV16x

1200Pa_H2O_40Cu-60Au_20keV1600Pa_H2O_40Cu-60Au_20keV

133Pa_H2O_40Cu-60Au_20keV53Pa_H2O_40Cu-60Au_20keV16x

400Pa_H2O_40Cu-60Au_20keV800Pa_H2O_40Cu-60Au_20keV

H 2 O

53 Pa H 2 O

High vacuum

1600 Pa H 2 O

1200 Pa H 2 O

800 Pa H 2 O

400 Pa H 2 O

133 Pa H 2 O

53 Pa H 2 O

High vacuum

Scaled to AuM

Photon energy (eV)

Photon energy (eV)

Counts

Relative Counts

16000

14000

12000

10000

8000

6000

4000

2000

0

0 500 1000 1500 2000250030003500400045005000

0 500 1000 1500 2000250030003500400045005000

. Fig. 25.7 DTSA-II Monte Carlo simulations of the specimen and gas scattering conditions of. Fig. 25.6. Upper plot: high vacuum and 53 Pa
(4 mm GPL, H 2 O). Lower plot: high vacuum and various pressures from 53 Pa to 1600 Pa

EDS

detector

Window

Collimator &

electron trap

Final

lens

Chamber

wall

BSE

BSE

Remote X-rays

Specimen X-rays

Green =

Extent of

specimen

X-ray sources

NOT excluded

by collimator

Several mm Several mm

. Fig. 25.8 Schematic diagram
showing the acceptance area of
the EDS collimator

25.1 · Gas Scattering Effects in the VPSEM