What absorbs at 3429 cm⁻¹ in an FTIR spectrum?
A band near 3429 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 3429 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) | 13 | 13 | 1.0 |
| Alkyl C-H | 4 | 4 | 1.0 |
| Silicon-oxygen (Si-O) | 3 | 3 | 1.0 |
| Silicon (Si) | 3 | 3 | 1.0 |
| N h | 3 | 3 | 1.0 |
| Hydrogen bond | 2 | 2 | 1.0 |
| Silanol (Si-OH) | 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 |
| Methyl | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| Siloxane (Si-O-Si) | 1 | 1 | 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 |
|---|---|---|---|
| nanotube | 3429, 1540, 1080 | Hydroxyl (O-H), Alkyl C-H | 1 |
| TiO2 | 3429, 1700, 1093 | Hydroxyl (O-H), Alkyl C-H | 1 |
| PVA | 3429, 1660, 2930 | Alkyl C-H, Hydroxyl (O-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 3429 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
“LLM confirmed rule peak-group candidate”
Arizka 等 - 2019 - Synthesis and Physical Properties Characterization DOI: 10.1088/1757-899X/546/4/042004 -
Hydrogen bond confidence 1.0
“LLM confirmed rule peak-group candidate”
Changes in chemical composition and structure of root cell wall of citrus rootstock seedlings in response to boron deficiency by FTIR spectroscopy DOI: 10.1080/14620316.2017.1362327 -
Hydroxyl (O-H) confidence 1.0
“The broad absorption cm-1 band observed at 3429 relates to the O-H stretching vibrations of water present in mixed monometallic iron manganese oxides and bimetallic FeMnO nano particles.”
Urea combustion synthesis of nano-structure bimetallic perovskite FeMnO3 and mixed monometallic iron manganese oxides: effects of preparation parameters on structural, opto-electronic and photocatalytic activity for photo-degradation of Basic Blue 12 DOI: 10.1007/s10854-017-6568-4 -
N h confidence 1.0
“peak at 3429 which was corresponding to NH group, which 2”
Covalent immobilization of Enterococcus faecalis Esawy dextransucrase and dextran synthesis DOI: 10.1016/j.ijbiomac.2015.09.076 -
Hydroxyl (O-H) confidence 1.0
“A broad band, which is cm-1, O-H ples besides the resulting defect and vacancies (Kumar found at 3429 refers to stretching vibration”
Structural and frequency-dependent dielectric properties of (SnO2)1-x(Fe2O3)x DOI: 10.1007/s11051-020-4763-3 -
Hydroxyl (O-H) confidence 1.0
“The relatively 2 cm-1 broad and intense absorption observed at around 3429 indicates the presence of bonded O-H cm-1 stretching vibration.”
Sathish 等 - 2013 - Nano Composite PVA-TiO2 Thin Films for OTFTs DOI: 10.4028/www.scientific.net/AMR.678.335 -
Hydroxyl (O-H) confidence 1.0
“S U cm-1, In the FTIR spectra of CTHIS, there is a wide -OH absorption peak at 3429 N which indicates that the phenolic compounds may be present in CTHIS.”
Pyrolysis characteristics of ethanol swelling Shendong coal and the composition distribution of its coal tar DOI: 10.1016/j.jaap.2018.12.012 -
Hydroxyl (O-H) confidence 1.0
“From the results, it was found that there was a stretching vibration of the O-H bond in the 3429 cm-1 to 2300 cm-1 region, a bending vibration of H-O- (a) 10 M NaOH Solution H in the 1595 cm-1 to 1628 cm-1 region and a stretching vibration”
Effective Utilization of Copper Slag for the Production of Geopolymer Concrete with Different NaOH Molarity under Ambient Curing Conditions DOI: 10.3390/su142316300
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