What absorbs at 1369 cm⁻¹ in an FTIR spectrum?
A band near 1369 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 1369 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 | 18 | 17 | 1.0 |
| Methacrylate | 7 | 7 | 1.0 |
| Acetate | 7 | 7 | 1.0 |
| Hydroxyl (O-H) | 7 | 7 | 1.0 |
| Methoxy (OCH3) | 5 | 5 | 1.0 |
| C-O single bond | 4 | 4 | 1.0 |
| Aromatic ring | 3 | 3 | 1.0 |
| Ester | 3 | 3 | 1.0 |
| Carboxyl (COOH) | 3 | 3 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| Boron nitrogen | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| S eq o | 1 | 1 | 1.0 |
| Sulfonate | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Silicon hydride | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Fluorine (C-F) | 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 |
|---|---|---|---|
| TiO2 | 1369, 1700, 1093 | Hydroxyl (O-H), Alkyl C-H, Methacrylate | 1 |
| TiO | 1369, 1730, 1699 | Alkyl C-H, Hydroxyl (O-H), Methacrylate | 1 |
| collagen | 1369, 1408, 1660 | 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 1369 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 peaks at 1369 and 897 cm-1 indicate the peaks of C-H deformation found in carbohydrates.”
n-Heptadecane-Impregnated Wood as a Potential Material for Energy-Saving Buildings DOI: 10.3390/f13122137 -
confidence 1.0
“spectra are nontrivial, since the similarities of masses between C-C For the CF 3-terminated acid (F17C9), the main feature in both the fluorine and carbon atoms and force constants between cm-1, C-F the ssp and ppp spectra is the peak at 1”
Tyrode 等 - 2007 - A study of the adsorption of ammonium perfluoronon DOI: 10.1021/jp063912h -
confidence 1.0
“The load plot of PC2 has C I 827/I F I 763/I 613 1654 seven positive weighted peaks around 1083, 1137, 1147, 1186, 1369cm-1.”
Wu 等 - 2023 - Infrared and Terahertz Spectra of Pu'er White Tea DOI: 10.1155/2023/3290917 -
Alkyl C-H confidence 1.0
“J Appl Polym Sci methylene band position (1369 position (1378 1996, 62, 1339.”
An effective method to identify the type and content of [alpha]-olefin in polyolefine copolymer by Fourier Transform Infrared-Differential Scanning Calorimetry DOI: 10.1002/app.30249 -
Hydroxyl (O-H) confidence 1.0
“The band centred at 1369 can be attributed to the O-H in-plane deformation mode of the alcohol [7].”
Augugliaro 等 - 2008 - Photocatalytic oxidation of aromatic alcohols to a DOI: 10.1016/j.apcata.2008.07.038 -
Alkyl C-H confidence 1.0
“The peak at 1369 cm-1 offers mainly information about the C-H bending vibrations [25].”
Variety Identification of Orchids Using Fourier Transform Infrared Spectroscopy Combined with Stacked Sparse Auto-Encoder DOI: 10.3390/molecules24132506 -
Alkyl C-H confidence 1.0
“The band at referred to H-C-H and O-C-H 1369cm-1 the absorbance intensity of the historical sample.”
Investigate the role of fungal communities associated with a historical manuscript from the 17th century in biodegradation DOI: 10.1038/s41529-022-00296-4 -
Alkyl C-H confidence 1.0
“cm(cid:3)1 The bands located at 1369, 1335 and 1315 were C-H O-H -CH assigned to the bending, in-plane bending and 2”
Surface hardness and flammability of Na2SiO3 and nano-TiO2 reinforced wood composites DOI: 10.1039/c9ra05200c
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