What absorbs at 3450 cm⁻¹ in an FTIR spectrum?
A band near 3450 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 3450 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) | 91 | 84 | 1.0 |
| Water (H2O) | 15 | 15 | 1.0 |
| N h | 11 | 10 | 1.0 |
| Alkyl C-H | 6 | 6 | 1.0 |
| Hydrogen bond | 6 | 5 | 1.0 |
| Silanol (Si-OH) | 6 | 5 | 1.0 |
| Amide | 5 | 4 | 1.0 |
| Carboxyl (COOH) | 3 | 3 | 1.0 |
| Carbonyl (C=O) | 3 | 3 | 1.0 |
| Metal oxygen | 3 | 2 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| C-O single bond | 2 | 2 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Ester | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| Carbohydrate | 2 | 2 | 1.0 |
| Phenolic | 2 | 2 | 0.8 |
| Secondary amine | 2 | 1 | 1.0 |
| Silicate | 1 | 1 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Metal hydroxyl | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| Amine primary | 1 | 1 | 0.8 |
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 |
|---|---|---|---|
| CuO | 3450, 453, 1000 | Hydroxyl (O-H) | 1 |
| SiO | 3450, 800, 1745 | Hydroxyl (O-H) | 1 |
| ZnO | 3450, 1400, 3430 | Hydroxyl (O-H), Alkyl C-H | 1 |
| zinc oxide | 3450, 1627, 1638 | Alkyl C-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 3450 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”
Synthesis of nickel oxide nanoparticles using pulsed laser ablation in liquids and their optical characterization DOI: 10.1016/j.apsusc.2012.03.147 -
Hydroxyl (O-H) confidence 1.0
“around 3400 1641 and 1092 Generally, in the FTIR spectra of silica, the USC cm-1 cm-1 absorption band around 3450 and 3400 are assigned to the stretching vibration of H-O-H and surface silanol group (Si-OH), respectively [19-20].”
Structural and optical investigations of Nd3+doped Y2O3-SiO2 nanopowder DOI: 10.1016/j.jallcom.2017.09.269 -
Hydroxyl (O-H) confidence 1.0
“cm(cid:1)1 (CONH-), (cid:4)1116 veried (O-H) a June meanwhile, peak at defects created in the crystal structure by incorporation of under cm(cid:1)1 different stretching.49 ions.58 metal The band at 3450 showed anti-symmetric 07 O-H bonds.”
Novel Ta/chitosan-doped CuO nanorods for catalytic purification of industrial wastewater and antimicrobial applications DOI: 10.1039/d2ra03006c -
Hydrogen bond confidence 1.0
“EPTE N5-H11 signals correspondence to hydrogen bonding are more intense than others in which cm-1, symmetric and asymmetric stretching modes shows absorption band at 3450 and 3702 respectively.”
Karimzadeh 等 - 2018 - FT-IR study and solvent-implicit and explicit effe DOI: 10.1016/j.saa.2018.03.009 -
Hydroxyl (O-H) confidence 1.0
“The broad peak at 3450 has been attributed to surface OH group vibrations.”
Kuthirummal 等 - 2016 - Synthesis and characterization of Ar-annealed zinc DOI: 10.1063/1.4964316 -
Hydroxyl (O-H) confidence 1.0
“(c c Wavenumber ) 3450 - -OH 1, 2) 3752 3752 -OH Stretching Fig.”
Synthesis characterization and luminescence studies of 100MeV Si8+ ion irradiated sol gel derived nanocrystalline Y2O3 DOI: 10.1016/j.nimb.2014.02.128 -
Hydroxyl (O-H) confidence 1.0
“Three OH bands cm-1 above 3450 are detected for both the natural and synthetic samples with negative temperature dependence, due to neighboring H-H repulsion in the crystal structure.”
In-situ high-temperature vibrational spectra for synthetic and natural clinohumite: Implications for dense hydrous magnesium silicates in subduction zones DOI: 10.2138/am-2019-6604 -
Hydroxyl (O-H) confidence 1.0
“ECS Journal of Solid State Science and Technology, 6 (7) R88-R95 (2017) R91 cm-1 cm-1 The absorption band at 3450 and 1630 can be attributed bond.51 to the symmetric stretching and bending vibration of H-O-H Theabsorptionbandobtainedat1386c”
Mondal 和 Manam - 2017 - Structural and Luminescent Properties of Si4+ Co-D DOI: 10.1149/2.0021708jss
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