What absorbs at 2923 cm⁻¹ in an FTIR spectrum?
A band near 2923 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 2923 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 | 85 | 77 | 1.0 |
| Hydroxyl (O-H) | 11 | 10 | 1.0 |
| Amide | 6 | 6 | 1.0 |
| Methyl | 6 | 6 | 1.0 |
| N h | 5 | 5 | 1.0 |
| Secondary amine | 5 | 5 | 1.0 |
| Carboxyl (COOH) | 5 | 5 | 1.0 |
| Methacrylate | 4 | 4 | 1.0 |
| Acetate | 4 | 4 | 1.0 |
| Lipid | 4 | 4 | 1.0 |
| Carbohydrate | 3 | 3 | 1.0 |
| Carbonyl (C=O) | 3 | 3 | 1.0 |
| Hydrogen bond | 3 | 3 | 1.0 |
| Alkene (C=C) | 2 | 2 | 1.0 |
| C n single bond | 2 | 2 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Ester | 2 | 2 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| Aromatic ring | 2 | 2 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Silicate | 1 | 1 | 1.0 |
| N-O bond | 1 | 1 | 1.0 |
| Fatty acid | 1 | 0 | 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 | 2923, 1700, 1093 | Hydroxyl (O-H), Alkyl C-H | 1 |
| Fe3O4 | 2923, 2358, 1673 | Hydroxyl (O-H), Alkyl C-H, Amide | 1 |
| Al2O3 | 2923, 1722, 1383 | Hydroxyl (O-H), Alkyl C-H | 1 |
| iron oxide | 2923, 1130, 891 | Alkyl C-H, Hydroxyl (O-H), Methyl | 1 |
| Fe3O4 nanoparticles | 2923, 1673, 1470 | Hydroxyl (O-H), Alkyl C-H, Amide | 1 |
| iron oxide nanoparticles | 2923, 2972, 528 | 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 2923 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
“All cm-1 to the O-H stretching, 2923 due to the C-H stretching, liquids were directly used as received and their surface tenthese cm-1 cm-1 1642 due to the H-O-H bending, 1155 due to the C-O sion and related components, e.g.”
Studies and comparison of the liquid adsorption and surface properties of α-, β- and γ-cyclodextrins by FTIR and capillary rise method DOI: 10.1016/j.colsurfa.2012.07.003 -
Alkyl C-H confidence 1.0
“The AGDM spectra showed the peaks at 3473 for the cm-1 NH-stretching, 2923 for asymmetrical CH stretching.”
Dhasmana 等 - 2019 - Silk fibroin protein modified acellular dermal mat DOI: 10.1016/j.msec.2018.12.038 -
Alkyl C-H confidence 1.0
“Peaks at 2923 and 2853 were mainly associated with the hydrocarbon chains of the lipids or lignins [40].”
Comparative Analysis of the Phenolic Profile of Lycium barbarum L. Fruits from Different Regions in China DOI: 10.3390/molecules27185842 -
confidence 1.0
“FTIR results cm-1 of HNO treated coal clearly indicated the presence of N-H group peak at 2923.04 in 3 cm-1, case of bituminous coal and introduction of the nitro group in lignite coal at 2921.84 while both peaks were absent in native coal”
Fatima 等 - 2021 - Extraction and Chemical Characterization of Humic DOI: 10.3390/su13168969 -
Alkyl C-H confidence 1.0
“The (OH stretch), 2923 (CH stretch), MATERIALS TECHNOLOGY 5 Figure 4.”
Functionalised nanoformulation of Swertiamarin with enhanced stability and hemocompatibility: synthesis, characterisation and anticancer evaluation DOI: 10.1080/10667857.2020.1769260 -
Hydroxyl (O-H) confidence 1.0
“The peak at 2922.98 cm belongs to the stretching vibration of OH which represents the stretching vibration of (PEG) -CH that is absorbed by Fe 3O 2”
ENHANCEMENT OF THERMAL IMAGING BY IRON OXIDE NANOPARTICLE – PRELIMINARY STUDY DOI: 10.1016/j.bcab.2018.12.005 -
Hydroxyl (O-H) confidence 1.0
“cm-1 cm-1 O-H C-H to stretching, sharp peaks at 2923.2 and 2854.2 were attributed to stretching, cm-1 was due to C = O of carboxyl groups.”
Kumar 和 Sidharth - 2018 - Some Studies on use of ternary blends of diesel, b DOI: 10.1080/15567036.2018.1486902 -
Alkyl C-H confidence 1.0
“Peaks at 2923 and 2852 corresponds to the 3 C-H stretching of hydrocarbon bonds of DDA, which are very weak in as composite powders.”
Structural, optical, morphological and thermal properties of TiO2–Al and TiO2–Al2O3 composite powders by ball milling DOI: 10.1016/j.physleta.2017.02.053
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