What absorbs at 1365 cm⁻¹ in an FTIR spectrum?
A band near 1365 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 1365 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 |
|---|---|---|---|
| Alkyl C-H | 15 | 15 | 1.0 |
| Methoxy (OCH3) | 9 | 9 | 1.0 |
| Methacrylate | 9 | 9 | 1.0 |
| Acetate | 9 | 9 | 1.0 |
| C-O single bond | 7 | 7 | 1.0 |
| Hydroxyl (O-H) | 3 | 3 | 1.0 |
| Methyl | 3 | 3 | 1.0 |
| Carboxyl (COOH) | 3 | 2 | 1.0 |
| Alkene (C=C) | 2 | 2 | 1.0 |
| S eq o | 2 | 2 | 1.0 |
| Secondary amine | 2 | 2 | 1.0 |
| C n single bond | 2 | 2 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| N h | 2 | 2 | 1.0 |
| Metal oxygen | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 0.9 |
| N-O bond | 1 | 1 | 0.9 |
| Water (H2O) | 1 | 1 | 0.9 |
| Carbonyl (C=O) | 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 |
|---|---|---|---|
| Al2O3 | 1365, 1722, 1383 | Methacrylate, Acetate, 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 1365 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
-
Alkyl C-H confidence 1.0
“The UL tion at 1427 cm-1 with a C-H deformation at 1365 cm-1, and carbohydrates at 897 cm-1 samples had significant chemical leaching during the decay test, resulting in a significant were observed.”
Can 等 - 2023 - Choline Chloride-Based Deep Eutectic Solvent-Treat DOI: 10.3390/f14030569 -
Alkyl C-H confidence 1.0
“The bands in the region of 1365cm-1 cm-1 1413 is assigned to the C-H bending vibrations.”
Gani 等 - 2017 - Physico-chemical, structural, pasting and thermal DOI: 10.1016/j.ijbiomac.2016.10.100 -
Carboxyl (COOH) confidence 1.0
“The band observed at ~1365 is assigned to the stretching vibration of carboxylate salts in the hydrogenated CeO sample”
Oxygen vacancies and F+ centre tailored room temperature ferromagnetic properties of CeO2 nanoparticles with Pr doping concentrations and annealing in hydrogen environment DOI: 10.1016/j.jallcom.2020.156079 -
Alkyl C-H confidence 1.0
“Peaks at 1365 are attributed to C-H deformation vibra300DF (1600cm(cid:3)1) tions (especially -CH 3) and aromatic C-C bond in”
Gradient separation of ⩾300°C distillate from low-temperature coal tar based on formaldehyde reactions DOI: 10.1016/j.fuel.2015.07.029 -
Alkyl C-H confidence 1.0
“21 O cm-1 1365 C-H stretching Carboxylate ions”
A.B. 等 - 2020 - Glucose electro-oxidation on Pt(100) in phosphate DOI: 10.1016/j.electacta.2020.136765 -
Alkyl C-H confidence 1.0
“Also compared to its respective untreated wood, some bands at 1365 cm-1 (C-H deformation in carbohydrate-related compounds [5]) and 670 (OH bending and out-of-plane stretching of hemicellulose-related compounds [1]) disappeared for the wood”
Acosta 等 - 2022 - Alumina as an Antifungal Agent for Pinus elliottii DOI: 10.3390/jof8121299 -
Alkyl C-H confidence 1.0
“The absorption bands at 1375 can be assigned 3 cm-1 to phenolic hydroxyls, and absorption bands at 1365 to symmetric deformation vibrations of C-H in methoxy groups [44].”
HPTLC and ATR/FTIR Characterization of Antioxidants in Different Rosemary Extracts DOI: 10.3390/molecules26196064 -
Alkyl C-H confidence 1.0
“When the FTIR spectra of sample W70 was examined, which was exposed to brown-rot fungi, there were noticeable cm-1 cm-1 changes in the peaks for the wavenumbers of 895 (C-H deformation), 1154 (Ccm-1 O-C vibrations), and 1365 (C-H deformatio”
Altuntas 等 - 2017 - Biodegradation Properties of Wood-plastic Composit DOI: 10.1002/app.24358
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