What absorbs at 3400 cm⁻¹ in an FTIR spectrum?
A band near 3400 cm⁻¹ can point to several functional groups. Below are the most likely assignments, ranked by how much published evidence supports each — every one traceable to literature (DOI) and cross-validated against our 130,000+ reference spectra and knowledge graph.
Backed by 8 cited sources
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Hydroxyl (O-H) | 146 | 131 | 1.0 |
| N h | 13 | 13 | 1.0 |
| Water (H2O) | 10 | 8 | 1.0 |
| Hydrogen bond | 3 | 3 | 0.9 |
| Alkyl C-H | 3 | 3 | 0.9 |
| Phenolic | 2 | 2 | 0.95 |
| Amide | 2 | 2 | 0.9 |
| Amine primary | 2 | 1 | 0.9 |
| Alkene (C=C) | 1 | 1 | 0.9 |
| Carboxyl (COOH) | 1 | 1 | 0.9 |
| Carbohydrate | 1 | 1 | 0.9 |
| Carbonyl (C=O) | 1 | 1 | 0.9 |
| Amino acid | 1 | 1 | 0.9 |
| Silanol (Si-OH) | 1 | 1 | 0.8 |
| C-O single bond | 1 | 1 | 0.6 |
| Carbonate | 1 | 1 | 0.6 |
| Protein | 1 | 1 | 0.6 |
| Acetate | 1 | 1 | 0.5 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Literature behind these assignments
-
Water (H2O) confidence 1.0
“The cm-1account bands around 3400 and 1630 for the presprominent The modes A 1g, B 1g, B and Eg are Raman active while A and 2g 2u ence of absorbed molecular water.”
Azam 等 - 2012 - Effect of Mn doping on the structural and optical DOI: 10.1016/j.jallcom.2012.01.072 -
confidence 1.0
“Explicit assignment.”
Dewi 等 - 2022 - Dual Modification of Sago Starch via Heat Moisture DOI: 10.3390/polym14061086 -
Hydroxyl (O-H) confidence 1.0
“Explicitly attributed to stretch OH group.”
Negim 等 - 2021 - Synthesis and characterization of polypropylene gl DOI: 10.31643/2021/6445.23 -
Hydroxyl (O-H) confidence 1.0
“OH band”
Krisanova 等 - 2022 - Amphiphilic anti-SARS-CoV-2 drug remdesivir incorp DOI: 10.1016/j.bbamem.2022.183945 -
Hydroxyl (O-H) confidence 1.0
“Explicitly assigned to O-H stretching vibrations.”
Niewes 等 - 2023 - Extraction of humic acid from peat and lignite and DOI: 10.1007/s10973-023-12326-7 -
Hydroxyl (O-H) confidence 1.0
“explicit assignment”
Pei 等 - 2019 - Removing Pb(II) Ions from Aqueous Solution by a Pr DOI: 10.3390/polym11030548 -
Hydroxyl (O-H) confidence 1.0
“Broad peak at ca. 3400 cm-1 characteristic for O-H group and associated to N-H stretching (Amide A).”
Perez-Puyana 等 - 2018 - Development of PVAgelatin nanofibrous scaffolds f DOI: 10.1088/2053-1591/aab164 -
Hydroxyl (O-H) confidence 1.0
“Broad band assigned to OH stretching”
Seslija 等 - 2018 - Physico-chemical evaluation of hydrophobically mod DOI: 10.1016/j.ijbiomac.2018.03.006
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