XPS peak assignments and atomic compositions for various species during mild steel corrosion in 20% formic acid containing 100 ppm 8b at 30 °C.

Species	Peak BE (eV)	Assignment	Atom%
Fe 2p	724.98	Fe–Ox	13.82
	711.08	Fe(OH)3/Fe2O3/FeCl3	54.69
	707.18	Fe–Ox/Fe–OH	8.03
	715.58	FeCl2/Fe(OH)2/FeO	12.29
	728.88	FeCl2	7.77
	720.28	Fe/Cu	3.40
C 1s	284.78	C–C	72.97
	288.38	C–N	27.03
N 1s	393.38	Organic matrix	31.56
	399.48	Organic matrix	24.35
	401.58	NR4+ salt	13.10
	404.38	—	0.81
	407.48	—	20.00
	414.28	—	10.18