SEM EDS

Question 1

What is the difference between K lines and L lines?

Answer 1

K lines go to K (inner) shell, whereas L lines only go to L shell (middle)

Question 2

Where does the source of the excitation come from?

Answer 2

Pre - disposed Electron beam from SEM / TEM

Question 3

What is used to detect the X rays and why?

Answer 3

A silicon drift detector, as it has high count rates, comparatively high energy resolution and theres no need to use liquid nitrogen cooling

Question 4

What is an important criteria of the K family to indentify an element?

Answer 4

Ratio of intensity of the Ka and Kb peak are approximately 10:1

Question 5

When are the K lines found?

Answer 5

EDS spectum

Question 6

When are the L lines found?

Answer 6

EDX spectrum

Question 7

What is the energy resolution of EDS/X

Answer 7

~ 140 eV

Question 8

Why may the data only show up as one peak?

Answer 8

Energy resolution too small

Question 9

What is the Quantification equation for concentration?

Answer 9

cA % = Na (specimen) / Na (standard)

Where Na is the number of X-rays

Question 10

What 3 effects need to be taken into account and to be corrected?

Answer 10

Atomic number effect (Z)

Self absorption effect (A)

Fluoresence effect (F)
X-rays generated may ionzie into making more X-rays

Question 11

WHy would a composition of SEM EDX analysis not add up to 100?

Answer 11

Errors, noted as wt% due to ZAF correction

Question 12

Is the average atomic weight = atomic weight of the pure element?

Answer 12

No

Question 13

What is the typical spatial resolution of EDS X-Ray microanalysis in the SEM?

Answer 13

2 μm

Question 14

What spectrum lines could you see at any accelerating voltage?

Answer 14

Any spectum lines with a smaller specific voltage (< 20Kv)