What absorbs at 3401 cm⁻¹ in an FTIR spectrum?
A band near 3401 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
Quick answer
A band near 3401 cm⁻¹ is usually interpreted by checking which functional groups repeatedly co-occur there in the literature, then confirming at least one or two additional peaks in the same sample. This page ranks those assignments by accumulated evidence rather than by a single fixed textbook rule.
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Hydroxyl (O-H) | 12 | 11 | 1.0 |
| N h | 7 | 5 | 1.0 |
| Water (H2O) | 2 | 2 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Phenolic | 1 | 1 | 0.9 |
| Ring structure | 1 | 0 | 1.0 |
| Secondary amine | 1 | 0 | 1.0 |
Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.
Possible materials
| Material | Supporting peaks | Overlapping groups | Cited sources |
|---|---|---|---|
| polyaniline | 3401, 1565, 1570 | Alkyl C-H | 1 |
| PMMA | 3401, 1722, 1383 | Alkyl C-H | 1 |
| lignin | 3401, 1035, 1510 | Alkyl C-H, Hydroxyl (O-H) | 1 |
| silver nanoparticles | 3401, 1636, 1631 | Hydroxyl (O-H), Alkyl C-H, N h | 1 |
Materials are shown only when the same literature pool supports this band and at least one additional characteristic peak.
Spectrum logic
This band becomes meaningful only when read with its neighboring peaks. In practice, analysts first look at the assignments above, then check whether the same sample also shows other peaks expected for the same structural motif. A lone band near 3401 cm⁻¹ is usually not enough for material identification by itself.
Real-world usage
This type of query is common in polymer identification, unknown plastic screening, QC troubleshooting, recycled-material verification, and literature-backed peak assignment review.
Common mistakes
- Treating one isolated band as proof of a material without checking at least one or two supporting peaks.
- Ignoring overlap: multiple functional groups can contribute near the same wavenumber.
- Skipping validation when additives, blends, oxidation, or contamination may distort the spectrum.
Verification advice
When ambiguity remains, validate the hypothesis with DSC, GC-MS, or TGA, especially for blends, degraded samples, and filled polymers.
Literature behind these assignments
-
Hydroxyl (O-H) confidence 1.0
“Obvious Fourier transform infrared cm-1, cm-1, (FTIR) spectra for the GT extract were observed, showing absorption bands at 3401 1628 cm-1, and 1029 corresponding to O-H/N-H, C=O, and C-O groups, respectively.”
Aziz 等 - 2017 - From Insulating PMMA Polymer to Conjugated Double DOI: 10.3390/polym9110626 -
N h confidence 1.0
“Explicit assignment in text”
Conversion of Sewage Water into H2 Gas Fuel Using Hexagonal Nanosheets of the Polyaniline-Assisted Deposition of PbI2 as a Nanocomposite Photocathode with the Theoretical Qualitative Ab-Initio Calculation of the H2O Splitting DOI: 10.3390/polym14112148 -
Hydroxyl (O-H) confidence 1.0
“Transmittance 75 -OH stretching 3400.83 3411.83 3417.98 C-H vibration 2897.18 2924.18 2926.11”
Effect of microwave assisted alkali pretreatment and other pretreatment methods on some properties of bamboo fibre reinforced cement composites DOI: 10.1016/j.conbuildmat.2020.118405 -
Hydroxyl (O-H) confidence 1.0
“A wide band was observed at 3401 which was attributed to the O-H and N-H stretching modes of polyphecm-1 at 3401 cm-1, which was attributed to the O-H and N-H stretching modes of polyphenols nols [50,51].”
Green Synthesis of Silver and Titanium Oxide Nanoparticles Using Tea and Eggshell Wastes, Their Characterization, and Biocompatibility Evaluation DOI: 10.3390/su151511858 -
Hydroxyl (O-H) confidence 1.0
“The recorded FTIR spectrum shows characteristic bands of a cellulose structure, such as a peak located at 3401 cm-1 that corresponds to the stretching of the O-H groups and a peak at 2902 cm-1 due to C-H stretching [30].”
Application of a Low-Cost Cellulose-Based Bioadsorbent for the Effective Recovery of Terbium Ions from Aqueous Solutions DOI: 10.3390/met10121641 -
Hydroxyl (O-H) confidence 1.0
“Open cm(cid:4)1) cm(cid:4)1), -O-H -C-H be stretching (3401 and 3124 stretching (1635 vibrations, as shown in Fig.”
Insight into carbon quantum dot–vesicles interactions: role of functional groups DOI: 10.1039/d1ra08809b -
Hydroxyl (O-H) confidence 1.0
“A wide band cm-1, was seen at 3401 and it has been reported that it is linked to the O-H and N-H stretching modes of polyphenols26,27.”
Tea from the drinking to the synthesis of metal complexes and fabrication of PVA based polymer composites with controlled optical band gap DOI: 10.1038/s41598-020-75138-x -
Hydroxyl (O-H) confidence 1.0
“In the case of Ac-lignin cm-1 as shown in Figure 5a, the wide absorption band at 3401 cm-1 originated from the presence of O-H as shown in Figure 5a, the wide absorption band at 3401 originated from the presence of O-H FTIR spectra of Ac-li”
Guo 等 - 2020 - The Influence of Compatibility on the Structure an DOI: 10.3390/polym12010056
Have a spectrum with this band?
Upload your FTIR spectrum and get a full interpretation report — peak assignments with literature citations, library matches, and a literature-backed analysis — in seconds.