What absorbs at 1265 cm⁻¹ in an FTIR spectrum?
A band near 1265 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 1265 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 |
|---|---|---|---|
| Methoxy (OCH3) | 12 | 11 | 1.0 |
| Methacrylate | 12 | 11 | 1.0 |
| C-O single bond | 12 | 11 | 1.0 |
| Acetate | 12 | 11 | 1.0 |
| Alkyl C-H | 5 | 5 | 1.0 |
| Lignin | 4 | 4 | 1.0 |
| Ring structure | 3 | 3 | 1.0 |
| Aromatic ring | 3 | 3 | 1.0 |
| Silicon carbon | 3 | 3 | 1.0 |
| Silicon-oxygen (Si-O) | 2 | 2 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| Phosphate (PO4) | 2 | 1 | 1.0 |
| Ammonium | 1 | 1 | 1.0 |
| Sulfate (SO4) | 1 | 1 | 1.0 |
| Fluorine (C-F) | 1 | 1 | 1.0 |
| Nitrogen heterocycle | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| Siloxane (Si-O-Si) | 1 | 1 | 1.0 |
| Protein | 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 |
|---|---|---|---|
| PDMS | 1265, 873, 1080 | Methoxy (OCH3), Methacrylate | 1 |
| PVA | 1265, 1660, 2930 | Acetate, Methacrylate, C-O single bond | 1 |
| plasma | 1265, 1656, 1650 | Methacrylate, Acetate | 1 |
| silver | 1265, 1636, 1310 | Methacrylate, Acetate | 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 1265 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
-
Acetate confidence 1.0
“The peak at 1265 cm-1 indicates C-O stretch lignin ring in guaiacyl units and 1026 C-O vibration in cellulose and hemicelluloses [33,34].”
n-Heptadecane-Impregnated Wood as a Potential Material for Energy-Saving Buildings DOI: 10.3390/f13122137 -
Acetate confidence 1.0
“The peak at 1265 indicated C-O stretching of the lignin ring in guaiacyl”
Can 等 - 2023 - Choline Chloride-Based Deep Eutectic Solvent-Treat DOI: 10.3390/f14030569 -
Aromatic ring confidence 1.0
“1159 Quinoid unit of doped anion N mode stretching band 1265 1230 1200 Aromatic C 1373 1370 1365”
Chabukswar 等 - 2012 - Studies on Synthesis and Effect of Dopants on Cond DOI: 10.1080/10601325.2012.722850 -
Protein confidence 1.0
“LLM confirmed rule peak-group candidate”
Depciuch 等 - 2022 - EFFECT OF HIGH BLOOD CORTISOL CONCENTRATION ON THE DOI: 10.21203/rs.3.rs-228476/v1 -
Silicon carbon confidence 1.0
“For column two the spectral data show that cm-1 in the spectrum were analyzed in detail for this study: the bands the ratio of the peak intensity of 1265 for film B divided cm-1 cm-1 (Si-CH (Si-O-Si cm-1 at 1265 symmetric bend), 1110 by the”
Piwowar 和 Gardella - 2008 - Reflection-absorption Fourier transform infrared s DOI: 10.1021/ma702893d -
C-O single bond confidence 1.0
“1265cm-1 cm-1 and of alkyl ether band at 1155-1060 droxyl groups change the crystalline structure of the (due to C-O stretch from the substituted benzyl ether) materials, when the intra and intermolecular hydrogen was observed.”
Uner 等 - 2016 - Wood Waste Turned Into Value Added Products Therm DOI: 10.5552/drind.2016.1534 -
Aromatic ring confidence 1.0
“2 cm-1 at 1448 was attributed to the aromatic stretching acrylic resin coating with the corresponding cm-1, cmband C=C while a few bands at 1265 1045 vibration mode is tabulated in Table 3.”
Zulkifli 等 - 2020 - Corrosion Resistance Evaluation of Acrylic Coating DOI: 10.17576/jkukm-2020-32(2)-14 -
Acetate confidence 1.0
“1328.80 CH-wagging 1241.93 C-O stretching of ether 1265.30 1087.13”
Abead 等 - 2023 - Study physical characteristics of Polyvinyl Alcoho DOI: 10.15764/pche.2014.02001.
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