What absorbs at 3520 cm⁻¹ in an FTIR spectrum?
A band near 3520 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 3520 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 | 12 | 1.0 |
| Water (H2O) | 3 | 3 | 1.0 |
| N h | 1 | 1 | 1.0 |
| N-O bond | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 0.9 |
| Silanol (Si-OH) | 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 |
|---|---|---|---|
| graphene oxide | 3520, 1150, 3400 | 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 3520 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
“Similarly, the wide vibration peak in 3520 frequency was related to OH group of water molecules on NPs surface.”
Farahmandjou 和 Motaghi - 2019 - Sol-gel synthesis of Ce-doped alpha-Al2O3 Study o DOI: 10.1016/j.optcom.2019.02.029 -
Hydroxyl (O-H) confidence 1.0
“The series of IR spectroH-O-H cm-1 (symmetric metric stretching) and 3520 scopic studies on the phase transitions of PVME, PiPA, H-O-Hstretching).20TheO-Hstretchingbandsofwater andotherpoly(N-substitutedacrylamide)sinwatershows (>50 in conc”
Maeda - 2001 - IR spectroscopic study on the hydration and the ph DOI: 10.1021/la001346q -
Hydroxyl (O-H) confidence 1.0
“cm-1 and the broad band at 3520 may be associated with the per2θ [O] turbation of OH groups through the surrounding by lattice defects or extra-lattice oxygen [49].”
IR study of iridium bonded to perturbed silanol groups of Pt-HZSM5 for n-pentane isomerization DOI: 10.1016/j.apcata.2011.12.039 -
N-O bond confidence 1.0
“on cm(cid:1)1 of electron from GO structure which was accepted by the elecThebroad peakat3520 corresponding tothe OHof NC Downloaded Commons cm(cid:1)1 decientO-NO shied groups(donor-accepterinteraction)of tron in NC/DEGDN sample weakened”
Yahya 等 - 2019 - Interaction and thermal studies on graphene oxide DOI: 10.1039/c9ra07717k -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
Preparation and Composition Optimization of PEO:MC Polymer Blend Films to Enhance Electrical Conductivity DOI: 10.3390/polym11050853 -
Hydroxyl (O-H) confidence 1.0
“The introduction of Mn into SiBEA zeolite led to the strong cm-1 decrease in the intensity of the bands at 3520 and 3705 related to OH groups forming”
Incorporation of Mn into the vacant T-atom sites of a BEA zeolite as isolated, mononuclear Mn: FTIR, XPS, EPR and DR UV-Vis studies DOI: 10.1039/c6cp01713d -
Hydroxyl (O-H) confidence 1.0
“However, a small shift of the OH band (previously centred at 3520 cm-1) cm-1 3520 to c.”
De Sa 等 - 2021 - Tracing Poly(Vinyl Acetate) Emulsions by Infrared DOI: 10.3390/polym13213609 -
Water (H2O) confidence 1.0
“Furthermore, water adsorbed on SiO shows a 2 cm-1 similar band at 3520 which is also preferentially polarised out of plane [23] and in general such high wavenumber bands are associated with free O-H.”
Microsoft Word - Frogley et al Polarised infrared microspectroscopy of edge-oriented graphene oxide papers.docx DOI: 10.1038/srep00085
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