What absorbs at 1576 cm⁻¹ in an FTIR spectrum?
A band near 1576 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 1576 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 |
|---|---|---|---|
| Aromatic ring | 5 | 5 | 1.0 |
| Carboxyl (COOH) | 5 | 4 | 1.0 |
| Alkene (C=C) | 4 | 4 | 1.0 |
| Amino acid | 2 | 2 | 1.0 |
| Alkyl C-H | 2 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Nucleic acid | 1 | 1 | 1.0 |
| Sulfur heterocycle | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 0.9 |
| Ring structure | 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 |
|---|---|---|---|
| nanocomposites | 1576, 1717, 1630 | Alkene (C=C) | 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 1576 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
-
Aromatic ring confidence 1.0
“The vibration band at 1576 cor6 responds to the quinoid ring units whereas lower frequency cm21 vibration band at 1476 depicts the presence of benzenoid ring units.”
Chutia 和 Kumar - 2015 - Electrical Transport and Morphological Studies of DOI: 10.1002/pen.23967 -
Sulfur heterocycle confidence 1.0
“Synthesis of PMOT/NiO nanocomposite The band thiophene ring were found at 1576 and 1398 cm-1 at 1092 has been identified as the stretching vibration of”
Sehgal 和 Narula - 2015 - Structural, morphological, optical, and electrical DOI: 10.1007/s00396-015-3663-z -
Alkene (C=C) confidence 1.0
“In cm-1 addition, rGO-7 and rGO-16 also sh howed C=C stretching at 1576 and 1586 which h are specific to cm-1 aromatic compounds and cyclohe exene.”
Sugianto 等 - 2019 - Facile Synthesis of Lycopene Reduced Graphene Oxid DOI: 10.1088/1757-899X/546/4/042044 -
Carboxyl (COOH) confidence 1.0
“Simultaas due to hydroxyl groups linearly coordinated to single cm-1, cm-1 neously, a couple of bands at 1576 and 1296 due to cations (Ce-Type I), and the most intense one at 3663 species,58 formate are developed.”
Collins 等 - 2007 - Hydrogen interaction with a ceria-zirconia support DOI: 10.1021/jp071968l -
Alkyl C-H confidence 1.0
“C=O stretching (ester groups) 2 C=O stretching (carboxyl COO1576 2880 CH symmetric stretching 1620 3”
Application of Vibrational Spectroscopic Techniques in the Study of the Natural Polysaccharides and Their Cross-Linking Process DOI: 10.3390/ijms24032630 -
Alkene (C=C) confidence 1.0
“At 77 K, a clear peak pair was observed at 1576 (-)/ cm-1, 1560 (+) which corresponds to the ethylenic C=C stretching vibration of MB and Batho.”
Hanai 等 - 2021 - Light-induced difference FTIR spectroscopy of prim DOI: 10.2142/biophysico.bppb-v18.005 -
Carboxyl (COOH) confidence 1.0
“metal soaps, narrow spectral windows were used for the including the carboxylate peaks at 1576 and 1541 integration to avoid spectral overlap.”
Henderson 等 - 2019 - Infrared chemical mapping of degradation products DOI: 10.1186/s40494-019-0313-7 -
Alkene (C=C) confidence 1.0
“(-)/1560 (+) surround the retinal chromophore (Figure A pair of peaks at 1576 corresponds to the C=C ethylenic stretching vibration of MB, and a spectral down-shift in this vibrational mode of the retinal cm-1 region7, chromophore at 1580-1”
Spectral Tuning Mechanism of Primate Blue-sensitive Visual Pigment Elucidated by FTIR Spectroscopy DOI: 10.1038/s41598-017-05177-4
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