Table 9 XPS spectral analysis for the surface products on API X60 steel after 24 h immersion in CO₂ -saturated 3.5% NaCl in the absence and presence of 50 ppm TBA at pH 4.

Blank

Fe2p

710.6

28.84

FeO, FeCO_3, Fe₂O_3, FeCl₂

⁵⁰

713.2

18.92

Fe₂O₃, FeOOH

⁵⁰

724.0

18.26

Fe₃O_4, Fe₂O₃

^16,51

O1s

529.4

30.29

Fe₂O₃, FeO

⁴⁹

530.0

7.74

Fe₂O₃, FeO

^49,50

530.9

42.97

FeOOH,

⁵²

531.9

18.99

C=O

^16,50

C1s

284.6

50.16

C-C

⁵¹

285.1

37.08

C-O-C

^49,53

288.4

12.77

-CO₃

^49,51

50

Fe2p

710.1

26.89

FeO_, Fe₂O_3, FeCl₂

⁵²

712.1

24.73

FeS, C=S_, FeOOH,

⁵⁴

723.8

19.75

Fe₃O_4, Fe₂O₃

⁵¹

O1s

529.5

16.91

Fe₂O₃, FeO

^16,49

530.2

35.95

Fe₂O₃, FeO

⁵²

531.2

36.97

FeOOH

^49,55

532.8

10.17

C=O

⁵³

C1s

284.2

9.50

C=C

⁵⁶

284.6

70.73

C-C

⁵¹

286.0

3.56

C=N

⁵³

287.8

6.57

C=O, C-N

^16,51

287.9

9.65

C=O, C-N

⁵⁷

S2p

167.6

34.82

C=S, SO₂

⁵⁸

162.0

65.18

FeS

^49,58