What absorbs at 2979 cm⁻¹ in an FTIR spectrum?
A band near 2979 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 5 cited sources
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Alkyl C-H | 5 | 4 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| Secondary amine | 1 | 0 | 1.0 |
| N h | 1 | 0 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Literature behind these assignments
-
Hydroxyl (O-H) confidence 1.0
“The peaks OH-stretching contribution in the region between ~3700 and ~3000 The cm-1 cm-1 at ~2979 cm-1 and ~2938 cm-1 are assigned to C-H stretching, while the peak centered at peaks at ~2979 and ~2938 are assigned to C-H stretching, while”
Hydrating Capabilities of the Biopolymers Produced by the Marine Thermophilic Bacillus horneckiae SBP3 as Evaluated by ATR-FTIR Spectroscopy DOI: 10.3390/ma15175988 -
Alkyl C-H confidence 1.0
“At 3009 in IR spectrum of oily vitamin A, C-H asymmetrical stretching from the CH2 groups of the oleic acid the IR spectrum of oily vitamin A, C-H asymmetrical stretching from the CH groups of the oleic 2 cm-1-theoretical cm-1) (2979 cm-1-t”
Spectroscopic Characterization of Emulsions Generated with a New Laser-Assisted Device DOI: 10.3390/molecules25071729 -
Carbohydrate confidence 1.0
“O-H stretching 2925 2925 C-H stretching of the pyranose ring 2979 -------- Symmetric stretching C-H of CH3 of Ethyl ester”
Flores-Hernandez 等 - 2021 - Synthesis of a Biodegradable Polymer of Poly (Sodi DOI: 10.3390/polym13040504 -
Alkyl C-H confidence 0.8
“C-H vibration”
Wang 和 Lin - 2005 - Reactions of trimethylindium on TiO2 nanoparticles DOI: 10.1021/jp050892v -
confidence 0.8
“Negative absorption at 2979 indicates desorption of -OCH2CH3 ligands.”
Cho 等 - 2015 - Mechanistic study of atomic layer deposition of Al DOI: 10.1116/1.4927318
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