Comparison of EDS Measurements
with Low-/High-energy Incident Electrons
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The accelerating voltage of electron beam in SEM for chemical micro-analysis using EDS is normally from 20 kV to 30 kV [1], while the accelerating voltages for TEM-EDS analysis are normally between 200 kV and 400 kV.

For effective generation of X-ray by ionization processed by electron interaction, the overvoltage U should be greater than 1.3 because the characteristic-to-continuum ratio (or the X-ray peak to background ratio, P/B) of X-ray signal is reduced substantially as E0 (energy of incident beam) approaches Ei (ionization energy). An overvoltage of ~ 2.0 generally results in a sufficient value of the peak-to-background to permit detection of concentration levels to trace levels for most elements. It is necessary to mention that the low energy X-ray lines, e.g. Cu(L) at 0.93 keV instead of Cu(K) at 8.04 keV, are used at low accelerating voltage of incident electrons.

For light element matrices the spatial resolution is substantially degraded. On the other hand, in light-element analysis it is also desirable to use a low accelerating voltage in the interest of minimizing absorption corrections. For instance, accelerating voltage down to 0.8 kV have been proved practical to distinguish very small (nm) inclusions of C in an O-rich ceramic matrix [2].

In comparison between EDS measurements of low- and high-energy incident electron beams, the low-energy method has the disadvantage of reducing the number of peaks in the spectrum that can be excited by the incident beam. Therefore, there are a number of peaks at these low energies and thus these peaks overlap, resulting in inaccurate elemental identification and quantification. However, For EDS measurements with high-energy beams, peak overlap may not be a critical problem so that the position and intensity of the high energy peaks can allow more accurate identification and quantification.

Furthermore, a typical problem in performing analysis at low beam energy is the effect of surface layer, which is different from the interior because of native surface oxidation, conductive coating for minimizing charging effect, and/or contamination. At high beam energy, the thickness of this surface layer is a small fraction of the excitation range so that the effect on EDS measurement is negligible. However, at low beam energy, the total sampling depth becomes so shallow that the surface layer contributes a significant fraction of the analyzed volume.

From Tables 4610a to 4610d, we can know that there are more peak overlaps between elements or more elements which are not detectable at low accelerating voltages.

Table 4610a. Periodic Table showing typical choices of X-ray lines for EDS operation in the range of accelerating voltages higher than 50 keV.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
     
1 H   2 He
                 
3 Li
 
4 Be
Kα 0.110
  5 B
Kα 0.183
6 C
Kα 0.277
7 N
Kα 0.392
8 O
Kα 0.525
9 F
Kα 0.677
10 Ne
Kα 0.848
   
You can download the excel file in order to highlight the elements in your EDS profile.
           
11 Na
Kα 1.041 
12 Mg
Kα 1.253
  Not detectable     K-shell      
  L-shell            
               
13 Al
Kα 1.486
14 Si
Kα 1.739
15 P
Kα 2.013
16 S
Kα 2.307
17 Cl
Kα 2.621
18 Ar
Kα 2.957 
                                     
19 K
Kα 3.312
 
   
 
 
20 Ca
Kα 3.690
 

   
 
  21 Sc
Kα 4.088
 

  
 
 
22 Ti
Kα 4.508
Kβ 4.931

  
 
  
 
23 V
Kα 4.949

 

 

 
  
24 Cr
Kα 5.411
 

 

 
   
25 Mn
Kα 5.894
 

 

    
26 Fe
Kα 6.398
 

 

    
27 Co
Kα 6.924
 

 

    
28 Ni
Kα 7.471
 

 
    
29 Cu
Kα 8.040
Kβ 8.91  
30 Zn
Kα 8.630
 

 
     
31 Ga
Kα 9.241  
 
 
   

 
32 Ge
Kα 9.874  
  

 
 
33 As
Kα 10.530
 
 
 
 
 
34 Se
Kα 11.207
 
 
 
 
 
35 Br
Kα 11.907
 
 
 
 
 
36 Kr
Kα 12.631
 
   
 

 
           
37 Rb
Kα 13.373
38 Sr
Kα 14.140
  39 Y
Kα 14.931
40 Zr
Kα 15.744
41 Nb
Kα 16.581
42 Mo
Kα 17.441
43 Tc
Kα 18.325
44 Ru
Kα 19.233
45 Rh
Kα 20.216
46 Pd
Lα 2.838
47 Ag
Lα 2.984
48 Cd
Lα 3.133 
49 In
Lα 3.286
50 Sn
Lα 3.443
51 Sb
Lα 3.604
52 Te
Lα 3.769
 
 
53 I
Lα 3.937
54 Xe
Lα 4.109
           
55 Cs
Lα 4.286
 
56 Ba
Lα 4.465
 
{57-70} 71 Lu
Lα 7.654
72 Hf
Lα 7.898
73 Ta
Lα 8.145
74 W
Lα 8.396  
75 Re
Lα 8.651  
76 Os
Lα 8.910
 
77 Ir
Lα 9.174  
78 Pt
Lα 9.441 
79 Au
Lα 9.712 
80 Hg
Lα 9.987 
81 Tl
Lα 10.267 
82 Pb
Lα 10.550  
83 Bi
Lα 10.837 
84 Po
Lα 11.129
 
85 At
Lα 
11.425 
86 Rn
Lα 
11.725 
                         
87 Fr
Lα 12.029
88 Ra
Lα 12.340
[89-102] 103 Lr
 
104 Rf
 
105 Db
 
106 Sg
 
107 Bh
 
108 Hs
 
109 Mt
 
110 Uun
 
111 Uuu
 
112 Uub
 
  114 Uuq
 
 
 
                               
{lanthanides} {57-70} 57 La
Lα 4.650
 
58 Ce
Lα 4.839
 
59 Pr
Lα 5.033
60 Nd
Lα 5.229
61 Pm
Lα 5.432   
62 Sm
Lα 5.635
63 Eu
Lα 5.845  
64 Gd
Lα 6.056 
65 Tb
Lα 6.272 
66 Dy
Lα 6.494
67 Ho
Lα 6.719
68 Er
Lα 6.947
69 Th
Lα 7.179
70 Yb
Lα 7.414
   
                           
{actinides} [89-102] 89 Ac
Lα 12.650 
90 Th
Lα 12.967
91 Pa
Lα 13.288
92 U
Lα 13.612
93 Np
Lα 13.942
94 Pu
Lα 14.276
95 Am
Lα 14.615
96 Cm
 

 
97 Bk
 

 
98 Cf
 

 
99 Es
 
 
100 Fm  
 
101 Md  
 
102 No  
 
   
 

 

Table 4610b. Periodic Table showing typical choices of X-ray lines for EDS operation in the range of accelerating voltages between 10 keV and 30 keV (U > 2 for Ec ≤ 10 keV).

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
     
1 H   2 He
                 
3 Li
 
4 Be
Kα 0.110
  5 B
Kα 0.183
6 C
Kα 0.277
7 N
Kα 0.392
8 O
Kα 0.525
9 F
Kα 0.677
10 Ne
Kα 0.848
   
You can download the excel file in order to highlight the elements in your EDS profile.
           
11 Na
Kα 1.041 
12 Mg
Kα 1.253
  Not detectable     K-shell     K- & L-shell
  L-shell     L- & M-shell     M-shell
               
13 Al
Kα 1.486
14 Si
Kα 1.739
15 P
Kα 2.013
16 S
Kα 2.307
17 Cl
Kα 2.621
18 Ar
Kα 2.957 
                                     
19 K
Kα 3.312
 

 
 
 
 
20 Ca
Kα 3.690
 

   
 
  21 Sc
Kα 4.088
 

  
 
 
22 Ti
Kα 4.508
Kβ 4.931

  
 
23 V
Kα 4.949

 

 

 
  
24 Cr
Kα 5.411
Lα 0.573
 
   
25 Mn
Kα 5.894
Lα 0.637
    
26 Fe
Kα 6.398
Lα 0.705
    
27 Co
Kα 6.924
Lα 0.776
    
28 Ni
Kα 7.471
Lα 0.851
    
29 Cu
Kα 8.040
Kβ 8.91
Lα 0.930
30 Zn
Kα 8.630
Lα 1.012
    
31 Ga
Lα 1.098
  
 
 

 
32 Ge
Lα 1.188
  
 
 

 
33 As
Lα 1.282
 

 

 
 
 
34 Se
Lα 1.379
 

 

 
 
 
35 Br
Lα 1.480

 

 

 
 
 
36 Kr
Lα 1.586

 

 
 
 

 
           
37 Rb
Lα 1.694
38 Sr
Lα 1.806
  39 Y
Lα 1.922
40 Zr
Lα 2.042
41 Nb
Lα 2.166
42 Mo
Lα 2.293
43 Tc
Lα 2.424
44 Ru
Lα 2.558
45 Rh
Lα 2.696  
46 Pd
Lα 2.838  
47 Ag
Lα 2.984  
48 Cd
Lα 3.133 
49 In
Lα 3.286
50 Sn
Lα 3.443
51 Sb
Lα 3.604
52 Te
Lα 3.769
53 I
Lα 3.937
54 Xe
Lα 4.109
           
55 Cs
Lα 4.286
 

 
56 Ba
Lα 4.465

 
{57-70} 71 Lu
Lα 7.654
M 1.581
 
72 Hf
Lα 7.898
M 1.644
 
73 Ta
Lα 8.145
M 1.709
 
74 W
M 1.774
 
 
75 Re
M 1.842
 
 
76 Os
M 1.914
 

 
77 Ir
M 1.977
 
 
 
78 Pt
M 2.048
 
 
 
79 Au
M 2.120
 
 
 
80 Hg
M 2.195
 
 
81 Tl
M 2.267
 
 
82 Pb
M 2.342
 
 
83 Bi
M 2.419
 
 
84 Po
 
   
 

 
85 At
 

 
 

 
86 Rn
 

 
 

 
                         
87 Fr 88 Ra [89-102] 103 Lr
 
104 Rf
 
105 Db
 
106 Sg
 
107 Bh
 
108 Hs
 
109 Mt
 
110 Uun
 
111 Uuu
 
112 Uub
 
  114 Uuq
 
 
 
                               
{lanthanides} {57-70} 57 La
Lα 4.650

 

 
58 Ce
Lα 4.839

 

 
59 Pr
Lα 5.033
M 0.929
60 Nd
Lα 5.229
M 0.978
61 Pm
Lα 5.432
 

 
 
62 Sm
Lα 5.635
M 1.081
63 Eu
Lα 5.845
M 1.131
 
64 Gd
Lα 6.056
M 1.185
 
65 Tb
Lα 6.272
M 1.240
 
66 Dy
Lα 6.494
M 1.293
67 Ho
Lα 6.719
M 1.347
68 Er
Lα 6.947
M 1.405 
69 Th
Lα 7.179
M 1.462
70 Yb
Lα 7.414
M 1.521
   
                           
{actinides} [89-102] 89 Ac
 
90 Th
M 2.991
91 Pa
M 3.077 
92 U
M 3.164
93 Np
M 3.260 
94 Pu
M 3.348
95 Am
M 3.437
96 Cm
M 3.539
97 Bk
M 3.634 
98 Cf
M 3.731
99 Es
 
 
100 Fm  
 
101 Md  
 
102 No  
 
   
 

 

Table 4610c. Periodic Table showing typical choices of X-ray lines for EDS operation at accelerating voltage of 5 keV (U > 1.1 for Ec ≤ 4.5 keV).

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
     
1 H   2 He
                 
3 Li
 
4 Be
Kα 0.110
  5 B
Kα 0.183
6 C
Kα 0.277
7 N
Kα 0.392
8 O
Kα 0.525
9 F
Kα 0.677
10 Ne
Kα 0.848
   
You can download the excel file in order to highlight the elements in your EDS profile.
           
11 Na
Kα 1.041
  
12 Mg
Kα 1.253
  Not detectable     K-shell      
  L-shell     M-shell, but are not sufficiently excited to be practically measured.
     
13 Al
Kα 1.486
14 Si
Kα 1.739
15 P
Kα 2.013
16 S
Kα 2.307
17 Cl
Kα 2.621
18 Ar
Kα 2.957 
         
19 K
Kα 3.312
    
20 Ca
Kα 3.690  
  21 Sc
Kα 4.088 

 
22 Ti
Lα 0.452
23 V
Lα 0.511  
24 Cr
Lα 0.573  
25 Mn
Lα 0.637  
26 Fe
Lα 0.705  
27 Co
Lα 0.776  
28 Ni
Lα 0.851  
29 Cu
Lα 0.930
30 Zn
Lα 1.012 
31 Ga
Lα 1.098  
32 Ge
Lα 1.188 
33 As
Lα 1.282 
34 Se
Lα 1.379 
35 Br
Lα 1.480
36 Kr
Lα 1.586
         
37 Rb
Lα 1.694
 
38 Sr
Lα 1.806
  39 Y
Lα 1.922
40 Zr
Lα 2.042
41 Nb
Lα 2.166
42 Mo
Lα 2.293
43 Tc
Lα 2.424
44 Ru
Lα 2.558
45 Rh
Lα 2.696  
46 Pd
Lα 2.838  
47 Ag
Lα 2.984  
48 Cd
Lα 3.133 
49 In
Lα 3.286
50 Sn
Lα 3.443
51 Sb
Lα 3.604
52 Te 53 I 54 Xe
                                     
55Cs 56 Ba {57-70} 71 Lu
M 1.581  
72 Hf
M 1.644  
73 Ta
M 1.709  
74 W
M 1.774  
75 Re
M 1.842  
76 Os
M 1.914  
77 Ir
M 1.977  
78 Pt
M 2.048  
79 Au
M 2.120  
80 Hg
M 2.195 
81 Tl
M 2.267  
82 Pb
M 2.342 
83 Bi
M 2.419 
84 Po
 
   
85 At
 

 
86 Rn
 

 
                         
87 Fr 88 Ra [89-102] 103 Lr
 
104 Rf
 
105 Db
 
106 Sg
 
107 Bh
 
108 Hs
 
109 Mt
 
110 Uun
 
111 Uuu
 
112 Uub
 
  114 Uuq
 
 
 
                               
{lanthanides} {57-70} 57 La 58 Ce
M 0.883
59 Pr
M 0.929
60 Nd
M 0.978
61 Pm
 
62 Sm
M 1.081
63 Eu
M 1.131 
64 Gd
M 1.185  
65 Tb
M 1.240  
66 Dy
M 1.293  
67 Ho
M 1.347  
68 Er
M 1.405 
69 Th
M 1.462 
70 Yb
M 1.521 
   
                           
{actinides} [89-102] 89 Ac
 
90 Th
M 2.991
91 Pa
M 3.077 
92 U
M 3.164
93 Np
M 3.260 
94 Pu
M 3.348
95 Am
M 3.437
96 Cm
M 3.539
97 Bk 98 Cf 99 Es  100 Fm 101 Md  102 No    
 

 

Table 4610d. Periodic Table showing typical choices of X-ray lines for EDS operation at accelerating voltage of 2.5 keV (U > 1.2 for Ec ≤ 2.2 keV).

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
     
1 H   2 He
                 
3 Li
 
4 Be
Kα 0.110
  5 B
Kα 0.183
6 C
Kα 0.277
7 N
Kα 0.392
8 O
Kα 0.525
9 F
Kα 0.677
10 Ne
Kα 0.848
   
You can download the excel file in order to highlight the elements in your EDS profile.
           
11 Na
Kα 1.041
  
12 Mg
Kα 1.253
  Not detectable     K-shell      
  L-shell     M-shell, but are not sufficiently excited to be practically measured.
     
13 Al
Kα 1.486
14 Si
Kα 1.739
15 P
Kα 2.013
16 S 17 Cl 18 Ar
                                     
19 K
 
 
20 Ca
Lα  0.341 
  21 Sc
Lα 0.395  
22 Ti
Lα 0.452 
23 V
Lα 0.511  
24 Cr
Lα 0.573  
25 Mn
Lα 0.637  
26 Fe
Lα 0.705  
27 Co
Lα 0.776  
28 Ni
Lα 0.851  
29 Cu
Lα 0.930
30 Zn
Lα 1.012 
31 Ga
Lα 1.098 
32 Ge
Lα 1.188 
33 As
Lα 1.282 
34 Se
Lα 1.379 
35 Br
Lα 1.480
36 Kr
Lα 1.586
         
37 Rb
Lα 1.694
38 Sr
Lα 1.806
  39 Y 40 Zr 41 Nb 42 Mo 43 Tc 44 Ru 45 Rh 46 Pd 47 Ag
 
48 Cd 49 In 50 Sn 51 Sb 52 Te 53 I 54 Xe
         
55 Cs 56 Ba {57-70} 71 Lu
M 1.581
 
72 Hf
M 1.644
 
73 Ta
M 1.709
 
74 W
M 1.774
 
75 Re
M 1.842
 
76 Os 77 Ir 78 Pt 79 Au 80 Hg 81 Tl 82 Pb 83 Bi 84 Po 85 At 86 Rn
                         
87 Fr 88 Ra [89-102] 103 Lr
 
104 Rf
 
105 Db
 
106 Sg
 
107 Bh
 
108 Hs
 
109 Mt
 
110 Uun
 
111 Uuu
 
112 Uub
 
  114 Uuq
 
 
 
                               
{lanthanides} {57-70} 57 La 58 Ce
M 0.883
59 Pr
M 0.929
60 Nd
M 0.978
61 Pm
 
 
62 Sm
M 1.081
63 Eu
M 1.131
64 Gd
M 1.185  
65 Tb
M 1.240  
66 Dy
M 1.293 
67 Ho
M 1.347 
68 Er
M 1.405 
69 Th
M 1.462 
70 Yb
M 1.521 
   
                           
{actinides} [89-102] 89 Ac  90 Th 91 Pa 92 U 93 Np 94 Pu 95 Am 96 Cm 97 Bk 98 Cf 99 Es  100 Fm  101 Md  102 No    
 

 

 

 

 

 

[1] R. Castaing, A. Guinier, Proceedings 1st International Congress on Electron Microscopy, Delft, 1950, p. 60.
[2] Edward D. Boyes, Analytical potential of EDS at low voltages, Mikrochim. Acta 138, 225-234 (2002).

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