What absorbs at 2959 cm⁻¹ in an FTIR spectrum?
A band near 2959 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 2959 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 | 28 | 26 | 1.0 |
| Methyl | 3 | 3 | 1.0 |
| Methoxy (OCH3) | 3 | 3 | 1.0 |
| Methacrylate | 3 | 3 | 1.0 |
| Acetate | 3 | 3 | 1.0 |
| Hydroxyl (O-H) | 3 | 3 | 1.0 |
| Carbohydrate | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| C-O single bond | 2 | 2 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| Aromatic ring | 2 | 2 | 1.0 |
| Nucleic acid | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| N-O bond | 1 | 1 | 1.0 |
| Lipid | 1 | 1 | 0.8 |
| Water (H2O) | 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 |
|---|---|---|---|
| calcium carbonate | 2959, 3232, 2954 | Alkyl C-H, Methoxy (OCH3), Methacrylate | 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 2959 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
-
Carboxyl (COOH) confidence 1.0
“between epoxide and carboxylic acid groups usually cm(cid:1)1, cm(cid:1)1, (cid:1)(cid:1)C(cid:1)(cid:1)H (cid:1)(cid:1)O(cid:1)(cid:1)H stretching at 2959 and takes place at high temperature leading to undesircm(cid:1)1.”
Synthesis, characterization, and curing of a new acrylate-based dental restorative resin DOI: 10.1002/app.28683 -
N-O bond confidence 1.0
“cm-1, cm-1 For the lipid region between 3050-2800 the three peaks at 2959 (asymmetpositive influence of PC1 had no peak.”
Specific Mycoparasite-Fusarium Graminearum Molecular Signatures in Germinating Seeds Disabled Fusarium Head Blight Pathogen’s Infection DOI: 10.3390/ijms22052461 -
Hydroxyl (O-H) confidence 1.0
“Figure.3 showed that the mid-strong 3451cm-1 peak at was the O-H stretching vibration absorption peak, the C-H stretching vibration cm-1,2959cm-1, 2929cm-1, 2879cm-1, 2746cm-1, absorption peaks were located at 3061 and the peaks 2247cm-1, 2”
Li 等 - 2011 - The detection of Cypermethrin on the surface of Ap DOI: 10.4028/www.scientific.net/AMR.287-290.2991 -
Alkyl C-H confidence 1.0
“3279 3275 3268 3275 3270 O-H stretching symmetric 2959 2959 2957 2959 2958 C-H stretching”
Fast non-destructive assessment of heavy metal presence by ATR–FTIR analysis of crayfish exoskeleton DOI: 10.1007/s11356-020-08405-z -
Alkyl C-H confidence 1.0
“oryzae 3524 7461 indicated that the strains have a higher frequency of the CH asymmetric stretching vibration at 3533 8387 8381 3 cm-1, 2959 the CH asymmetric stretching vibration at”
Wang 等 - 2012 - Differentiation in MALDI-TOF MS and FTIR spectra b DOI: 10.1186/1471-2180-12-182 -
Alkyl C-H confidence 1.0
“In particularly in ATX3-Q55, we observed an increase of the intensity of the CH bands 2 particular, the spectra of NI cells are characterized by four main bands: ~2959 cm-1 (CH3 cm-1 cm-1 at ~2921 and 2852 compared to NI cells.”
Pathological ATX3 Expression Induces Cell Perturbations in E. coli as Revealed by Biochemical and Biophysical Investigations DOI: 10.3390/ijms22020943 -
Alkyl C-H confidence 1.0
“In a, b second derivative spectra have been normalized cm-1, normalized to the tyrosine band at ~1516 while in c spectra cm-1, to the tyrosine band at ~1516 while in c spectra have been cm-1 have been normalized at the CH band at ~2959 3 cm”
Protein aggregation and membrane lipid modifications under lactic acid stress in wild type and OPI1 deleted Saccharomyces cerevisiae strains DOI: 10.1186/s12934-016-0438-2 -
confidence 1.0
“Explicit assignment in table.”
Cakmak-Arslan 等 - 2020 - Investigation of the Toxic Effects of Rhododendron DOI: 10.9775/kvfd.2019.22996
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