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Table 1 Assignment of main infrared peaks (cm−1) of standard materials and compounds

From: Erratum to: A study of the deterioration of aged parchment marked with laboratory iron gall inks using FTIR‑ATR spectroscopy and micro hot table

Absorption maximum (cm−1)

Assignment

Collagenous materials

Collagen

Parchment

3315 s, br

3302

Amide A: first component of vN–H in Fermi resonance with the amide II overtone (overlapping with v as O–H (3447 br) and v s O–H (3240 br) of structural H2O)

3072, m-w, br

3072

Amide B: (second component of vN–H in Fermi resonance with the amide II overtone)

2958

2926

vC–H

1640 s

1644

Amide I: vC=O with small contributions from vC–N and δN–H) [overlapping with δH–O–H (approx. 1610) of structural H2O]a

1545 s

1538

Amide II: (vC–N with contributions from δ ip N–H)b

1454 m-w

1448

δCH2 of Pro-

1405 w

1408

δ ip C–O–H (carboxylic side chains) and δNH2

1340 w

1334

wCH2/δC–H (methine)

1241 m-w

1230

Amide III: (vC–N + δN–H with contributions from vC–C and δipC=O)b

1082, 1032

1084, 1031

Breathing of proline ring [68] with carbohydrate vC–O and vC–O–C (glycosylation sites) [69]/parchment: additional esters [70]

Gallic acid [40, 73, 74]

3498

vO9H, vO11H

3366

vO10H

3284

vO14H (COOH)

3065, 2996, 2844

vC2–H, vC6–H

2673, 2632, 2575, 2512

vO14H (–COOH dimers)

1703

vC=O

1668, 1648

vC=O (–COOH dimers)

1612,1542,1484, 1468, 1427, 1387, 1321

vC=C (aromatic ring vibrations)

1268

vC–O

1221

δ(i-p) C–O–H

1184

vC1–C7+ vC–H

1099

vC1–C7+ δC–O–H

1028

Aromatic asym-, sym-breathing, vC1–C7 + vC–OH (phenol)

904

vC-O +δ(o-o-p) C-O-H (dimer band) + δ(o-o-p) of ring

867

δ(i-p) C–H

767

δ(o-o-p) C–H (out-of-phase)

735

δ(o-o-p) C–H (out-of-phase) + τC–OH (torsion)

703

Aromatic ring puckering

636

Aromatic ring puckering + δ(o-o-p) C–O–H (phenolic)

559

δ(o-o-p) C–O–H (phenolic)

492

τC—aromatic ring

Gum Arabic

3352

vOH

2932

vC–H

1604

v as COO

1418

v s COO

1146(sh), 1068, 1035(sh)

vC–O

Iron (II) sulfate heptahydrate

3336

vOH

1652

δOH in water

1092

v 3 SO4 2−

977

v 1 SO4 2−

619

v 4 (asym-) SO4 2−

LIG ink formulation

3415

vOH in water

1645

δOH in water

1094

v 3 SO4 2−

977

v 1 SO4 2−

628

v 4 (asym-) SO4 2−

LIGG ink formulation

3439

vH–O in polysaccharide (gum Arabic) and water

2931

vC–H

1640

δOH in water overlapping with v asCOO in polysaccharide (gum Arabic)

1424

v s COO in gum Arabic

1083

v 3 SO4 2− overlapping with vC–O in gum Arabic

1146(sh), 1035(sh)

vC–O in gum Arabic

604

v 4 (asym-) SO4 2−

  1. v stretching, δ bending, d deformation, ip in-plane, sh shoulder
  2. aAccording to Ref. [24]
  3. bAccording to Refs. [24, 46]