Biomedical Engineering Reference
In-Depth Information
The N 1s peak showed a main component at 400.0 eV attributed to amide or amine (N-C).
An additional component appeared clearly near 401.6 eV in silanized SS samples (sil and
sil+Gox, Figure 3), indicating the presence of protonated amines. The contributions at lower
binding energies in the N 1s spectral window are due to Mo 3p
3
/
2
components (Olefjord &
Wegrelius, 1996); the reliability of their quantification was checked by comparison with the
Mo concentration deduced from the Mo 3p
3/2
and Mo 3d peaks (Landoulsi et al., 2008a). The
N 1s contribution of sil shows a shape which is in agreement with spectra reported in the
literature for APTES-modified surfaces (Suzuki et al., 2006; Xiao et al., 1997). It was not
found justified to decompose it in three components attributed to amine, amide and
protonated amine, respectively, as done in (Suzuki et al., 2006). The surface concentrations
(mole fraction) associated with the components of C 1s, O 1s and N 1s peaks are given in
Table 2.
Ni
ox
Ni
met
Ni
tot
Fe
ox
Fe
met
Fe
tot
Cr
ox
Cr
met
Cr
tot
Mo
ox
Mo
met
Mo
tot
Si
0
nat
1.23
0.73
1.95
7.59
1.57
9.16
4.69
0.33
5.02
0.34
0.12
0.46
0.38
+BS
0.81
0.54
1.35
8.32
1.89
10.21
5.96
0.40
6.36
0.46
0.12
0.57
0.29
+Gox
0.59
0.51
1.10
8.63
1.70
10.33
5.53
0.33
5.86
0.37
0.12
0.49
-
+BS+Gox
0.66
0.39
1.05
8.90
1.43
10.33
4.56
0.30
4.87
0.32
0.12
0.44
0.36
sil
0.47
0.33
0.80
7.89
1.22
9.10
4.59
0.27
4.86
0.31
0.10
0.40
0.37
sil+BS
0.47
0.43
0.91
6.91
1.45
8.36
5.24
0.33
5.57
0.35
0.11
0.45
0.32
sil+Gox
0.60
0.38
0.98
6.14
1.29
7.42
4.95
0.29
5.23
0.32
0.12
0.44
0.26
sil+BS+Gox
0.54
0.32
0.86
6.22
1.16
7.39
4.58
0.24
4.82
0.34
0.09
0.42
0.30
C
288.7
C
287.8
C
286.3
C
284.8
O
533.1
O
531.2
O
529.7
C
tot
O
tot
O
org
N
401.6
N
400
N
tot
Si
org
∑org
nat
2.45
2.29
3.92
39.62
48.28
2.36
19.02
12.60
33.98
7.92
0.00
0.73
0.73
0.44
57.37
+BS
2.89
2.08
3.88
34.87
43.71
2.48
18.96
13.86
35.30
7.64
0.00
1.21
1.21
0.43
52.99
+Gox
2.03
2.16
4.78
35.56
44.53
2.97
20.96
11.27
35.20
7.50
0.13
1.34
1.48
-
53.50
+BS+Gox
2.55
2.60
5.89
30.02
41.06
3.96
22.01
12.57
38.54
9.46
0.23
1.35
1.58
0.89
52.99
sil
1.15 2.37 4.57 36.13
44.23
1.95 21.22 12.28
35.45 5.93
0.63 1.54
2.17 2.29 54.61
sil+BS
2.03 3.30 6.48 32.72
44.53
1.07 23.16 9.71
33.94 8.49
0.66 2.65
3.31 2.13 58.47
sil+Gox
1.18 5.97 10.39 25.08
42.62
4.74 21.09 8.86
34.70 11.78
0.59 5.16
5.75 1.74 61.90
sil+BS+Gox
1.46 4.89 8.31 30.39
45.05
2.87 22.24 8.52
33.63 9.86
0.50 4.30
4.80 2.01 61.72
Table 2. Surface concentration (mole fraction (%) computed over the sum of all elements
except hydrogen) of elements determined by XPS (
θ
= 0°) on stainless steel samples.
The Si 2p peak was decomposed in two components, at 99.3 and 101.8 eV, attributed to non
oxidized silicon in SS (Si
0
) and to silicon of silane (Si
org
), respectively. It was not decomposed
in Si 2p
3/2
and Si 2p
1/2
contributions because these are very close in energy. The
decomposition procedure for Fe 2p
3/2
, Cr 2p, Ni 2p
3/2
, and Mo 3d peaks was described
before (Landoulsi et al., 2008a). The Fe concentration may be underestimated due to the
procedure used to treat the complex baseline of the Fe 2p peak. The distinction between
contributions of oxidized (M
ox
) and nonoxidized (M
met
) metal elements was easily made.
The concentrations obtained are also given in Table 2.
The concentration of oxygen present in organic compounds
O
org
may not directly be
deduced from the O 1s
peak owing to the overlap with inorganic hydroxide. However, for
biological systems the sum of O and N concentrations may be evaluated by the
