What absorbs at 2965 cm⁻¹ in an FTIR spectrum?
A band near 2965 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 2965 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 | 23 | 22 | 1.0 |
| N h | 5 | 5 | 1.0 |
| Hydroxyl (O-H) | 4 | 4 | 1.0 |
| Amide | 4 | 4 | 1.0 |
| Methyl | 4 | 3 | 1.0 |
| Methacrylate | 4 | 3 | 1.0 |
| Acetate | 4 | 3 | 1.0 |
| Carboxyl (COOH) | 3 | 3 | 1.0 |
| Secondary amine | 3 | 3 | 1.0 |
| C-O single bond | 2 | 2 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Ester | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| Methoxy (OCH3) | 2 | 1 | 1.0 |
| C c single bond | 2 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Silicon carbon | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Lipid | 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 |
|---|---|---|---|
| graphene oxide | 2965, 1150, 3400 | Hydroxyl (O-H), 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 2965 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 peak at 2965 corresponds to asymmetric stretching cm-1 vibrations of CH group in lipids, while band 1645 corresponds to C=O stretching 3 α-helix of proteins.”
A Preliminary Study of FTIR Spectroscopy as a Potential Non-Invasive Screening Tool for Pediatric Precursor B Lymphoblastic Leukemia DOI: 10.3390/molecules -
Alkyl C-H confidence 1.0
“The overlappinng though their contribution to the CH vibrations cannot be totally of these two kinds of absorptions makes difficult the spectral ruledout.Anabsorptionat2965cm¡1hasbeenreportedintheIR interpretation.”
Modification of Chrysotile Surface by Organosilanes: An IR–Photoacoustic Spectroscopy Study DOI: 10.1006/jcis.2001.7524 -
Hydroxyl (O-H) confidence 1.0
“Obtained Wavenumber Reference Wavenumber Functional Group/Fingerprint ObtainedWavenumber ReferenceWavenumber FunctionalGroup/Fingerprint cm-1 cm-1 2965.11 ±3000 (Strong & Board) -COOH (O-H Stretching) 2965.11cm-1 ±3000cm-1 -COOH(O-HStretchi”
Validation of the Developed Zero-Order Infrared Spectrophotometry Method for Qualitative and Quantitative Analyses of Tranexamic Acid in Marketed Tablets DOI: 10.3390/molecules26226985 -
Secondary amine confidence 1.0
“However, for the particles, we can notice that the suggests the predominance of secondary amine NH stretching cm-1 (ϕ-NH-R) peak at 2965 is dominating, whereas for the coatings it is modes, probably corresponding to aryl-amine cm-1 C-N-H th”
Pereira 等 - 2006 - Characterization of a-CNx H particles and coating DOI: 10.1016/j.surfcoat.2005.11.004 -
Alkyl C-H confidence 1.0
“The set of bands cm-1 between 2965 and 2876 are basically assigned to CH vibration in cellulose and hemicellulose of 2”
Pereira 等 - 2020 - Ballistic Performance of Ramie Fabric Reinforcing DOI: 10.3390/polym12112711 -
Alkyl C-H confidence 1.0
“(ss) stretch and the Fermi resonance (FR) of the CH bending 3 salts.73 benzene molecule, which is noticeable for both ∼2965 cm-1, overtone.”
GasLiquid Interface of Hydrophobic and Hydrophilic Room-Temperature Ionic Liquids and Benzene: Sum Frequency Generation and Surface Tension Studies DOI: 10.1021/jp803177w -
Silicon carbon confidence 1.0
“The cm(cid:2)1 and beyond which the aerogel underwent significant loss in its presence of Si-CH peaks at 2965 and 850 clearly 3 weight.Thisreferstotheoxidationofthe-CH 3groupsfromthe confirms the surface modification of the aerogels.”
Sarawade 等 - 2007 - High specific surface area TEOS-based aerogels wit DOI: 10.1016/j.apsusc.2007.06.063 -
Alkyl C-H confidence 1.0
“suggestingthepreferentialdecomposition ofmethylenealiphatic - - 1 1 - C /H : 1600 cm band/2965 2850 cm zone groups.49 This was suggested to be due to the loss of alkyl chains ar al (2) and conversion of the hydroaromatic methylene structure”
Tahmasebi 等 - 2012 - Study of Chemical Structure Changes of Chinese Lig DOI: 10.1021/ef300559b
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