What absorbs at 3079 cm⁻¹ in an FTIR spectrum?
A band near 3079 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
Quick answer
A band near 3079 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 | 2 | 2 | 1.0 |
| Alkene (C=C) | 2 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Sulfur heterocycle | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
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 3079 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
-
C c single bond confidence 1.0
“The C C bonds appear in the weak bands 2931 and 3079cm-1 ∼1635cm-1 at (C C H) and (C C).”
Font 等 - 2007 - Fourier transform infrared spectroscopy as a suita DOI: 10.1016/j.aca.2007.07.021 -
confidence 1.0
“In GaAs grown by liquid encapsulation Czochralski (LEC), the peaks at 3079.2 and 983.3cm(cid:2)1 due to the stretching and wagging mode of N-H were observed at 7K, where its concentration was in 1013cm(cid:2)3 1012 the range from to [15].”
Nishimura 等 - 2007 - Electrical properties of GaAsN film grown by chemi DOI: 10.1016/j.physb.2007.08.183 -
Amide confidence 1.0
“The absorption of amide B at 3079 showed acid soluble collagen content of 3.7 ± 0.8% of was related to the asymmetric stretching vibrations of C-H the wet mass weight of the skin and protein content of”
Valorization of Salmo salar Skin Waste for the Synthesis of Angiotensin Converting Enzyme-1 (ACE1) Inhibitory Peptides DOI: 10.1007/s12649-023-02141-4 -
Alkyl C-H confidence 1.0
“LLM confirmed rule peak-group candidate”
Rapid Classification and Recognition Method of the Species and Chemotypes of Essential Oils by ATR-FTIR Spectroscopy Coupled with Chemometrics DOI: 10.3390/molecules27175618 -
Sulfur heterocycle confidence 1.0
“A peak at 3079 cm-1 in the FTIR spectra of monomer TEBS is due to cm´1 thiophene ring.”
Enzyme-Catalyzed Synthesis of Water-Soluble [1.0]Conjugated Poly[2-(3-thienyl)-Ethoxy-4-Butylsulfonate] DOI: 10.3390/polym8040139
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