What absorbs at 3436 cm⁻¹ in an FTIR spectrum?
A band near 3436 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 3436 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) | 28 | 28 | 1.0 |
| N h | 7 | 6 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| Hydrogen bond | 2 | 2 | 1.0 |
| Water (H2O) | 2 | 2 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| N c o | 1 | 1 | 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 |
|---|---|---|---|
| calcite | 3436, 2850, 2864 | Hydroxyl (O-H), Alkyl C-H | 1 |
| apatite | 3436, 3053, 1640 | Hydroxyl (O-H), Alkyl C-H | 1 |
| chitosan | 3436, 1650, 1655 | Alkyl C-H, Hydroxyl (O-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 3436 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”
Bohari 等 - 2022 - Synthesis and Characterization of 2,4-Dichlorophen DOI: 10.22146/ijc.73546 -
Hydroxyl (O-H) confidence 1.0
“The small absorption bands at cm-1 3436 and 1620 are assigned to O-H stretching and bending vibrations respectively.”
Francis 等 - 2016 - Optical nonlinearity in multiferroic bismuth ferri DOI: 10.1016/j.jallcom.2016.07.094 -
Hydroxyl (O-H) confidence 1.0
“The cm-1 cm-1 peak at 3436 can be attributed to the stretching mode of -OH.”
Karuppannan 和 Prashantha - 2010 - Nano structured carbon nitrides prepared by chemic DOI: 10.1117/12.861609 -
Hydroxyl (O-H) confidence 1.0
“The intense bands at 3436 and 1640 are attributed to the ν(O-H) mode and δ(OH) of H 2O molecules that are linked to CeO 2-NPs, respectively [35].”
Biosynthesis, characterization and cytotoxic activity of CeO2 nanoparticles DOI: 10.1016/j.ceramint.2018.04.063 -
Hydroxyl (O-H) confidence 1.0
“As previously reported, the peak that represents the O-H cm-1 cm-1 stretching at 3436 shifted to 3386 when the powder of the carboxymethyl kappa carrageenan was dissolved in 1% acetic acid [4].”
Mobarak 等 - 2015 - Carboxymethyl Carrageenan Based Biopolymer Electro DOI: 10.1016/j.electacta.2015.02.200 -
Water (H2O) confidence 1.0
“3 cm1, 4(A) shows that a broad band around 3436 and 1632 which are assigned to the stretching and bending modes of In the spectrum of Figure 4(A)(a), exadsorbed water [24].”
Wang 等 - 2014 - Chelating agents role on phase formation and surfa DOI: 10.1007/s11426-013-4961-2 -
Water (H2O) confidence 1.0
“The stretching vibrations of adsorbed water molecules were responsible cm-1 for the band at 3436 [25].”
Abdel-Halim 等 - 2023 - Apatite-Calcite Flotation Separation Using Sodium DOI: 10.3390/min13070970 -
Hydrogen bond confidence 1.0
“LLM confirmed rule peak-group candidate”
Abu Elella 等 - 2021 - One-pot green synthesis of antimicrobial chitosan DOI: 10.1039/d1ra07070c
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