What absorbs at 1580 cm⁻¹ in an FTIR spectrum?
A band near 1580 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 1580 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 |
|---|---|---|---|
| Amide | 21 | 20 | 1.0 |
| N h | 17 | 17 | 1.0 |
| Alkene (C=C) | 14 | 13 | 1.0 |
| Carboxyl (COOH) | 13 | 9 | 1.0 |
| Aromatic ring | 12 | 11 | 1.0 |
| Methacrylate | 9 | 8 | 1.0 |
| Acetate | 9 | 8 | 1.0 |
| Secondary amine | 8 | 7 | 1.0 |
| Methoxy (OCH3) | 7 | 6 | 1.0 |
| C-O single bond | 7 | 6 | 1.0 |
| Alkyl C-H | 7 | 5 | 1.0 |
| Carbonyl (C=O) | 5 | 5 | 1.0 |
| C c single bond | 5 | 3 | 1.0 |
| Hydrogen bond | 4 | 4 | 1.0 |
| C n single bond | 4 | 3 | 1.0 |
| Hydroxyl (O-H) | 4 | 3 | 1.0 |
| Ketone | 3 | 3 | 1.0 |
| Ester | 3 | 3 | 1.0 |
| C=n | 2 | 2 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Nitrogen heterocycle | 1 | 1 | 1.0 |
| Nitro (NO2) | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Aldehyde (CHO) | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Chitosan | 1 | 1 | 1.0 |
| Silicon nitrogen | 1 | 0 | 1.0 |
| Silicon (Si) | 1 | 0 | 1.0 |
| N-O bond | 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 |
|---|---|---|---|
| chitosan | 1580, 1650, 1655 | Amide, N h | 1 |
| polycaprolactone | 1580, 1751, 1724 | Amide | 1 |
| PANI | 1580, 2930, 1300 | N h, Amide, Alkene (C=C) | 1 |
| bitumen | 1580, 1625, 810 | N h, Carboxyl (COOH) | 1 |
| dentin | 1580, 575, 1740 | Amide, Carboxyl (COOH) | 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 1580 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
-
confidence 1.0
“These spectra verify that the observed N-H cm-1 and some bending, while the mode at 1580 is vibrationalmodesinFigure1A,BofaPBA-SAMonagold N-H cm-1 primarily a bending mode.”
Brewer 等 - 2004 - Infrared detection of a phenylboronic acid termina DOI: 10.1021/la035037m -
Amide confidence 1.0
“The 1630 peak corresponds to the stretching vibration of C¼¼O bond cm-1 (mC¼¼O) from amide I, and the 1580 peak corresponds”
Root canal hydrophobization by dentinal silanization: Improvement of siliconbased endodontic treatment tightness DOI: 10.1002/jbm.b.32874 -
Aromatic ring confidence 1.0
“with absorption at 1580 prominent feature in the meridional direction of the thus, this peak is only characteristic of the terephthalate rings in the amorhigh BB content fibers.”
Ma 等 - 2004 - Crystal structure and composition of poly(ethylene DOI: 10.1021/ma0486905 -
Chitosan confidence 1.0
“The main peaks of the spectrum of chitosan included 3400 cm-1 and 1580 cm-1, 1580 which were assigned to the -OH and -NH stretching, and the amide II bands”
Plasma-Induced Graft Polymerization of Polyethylenimine onto Chitosan/Polycaprolactone Composite Membrane for Heavy Metal Pollutants Treatment in Industrial Wastewater DOI: 10.3390/coatings12121966 -
C=n confidence 1.0
“LLM confirmed rule peak-group candidate”
Properties of conductive PANI fabricated using different dopant acids and molar ratios DOI: 10.1063/5.0015755 -
Aromatic ring confidence 1.0
“LLM confirmed rule peak-group candidate”
Improvement of anti-corrosion performance of an epoxy coating using hybrid UiO-66-NH2/carbon nanotubes nanocomposite DOI: 10.1038/s41598-022-14854-y -
Acetate confidence 1.0
“The peaks at 1580, 1358, 1159 and 1060 cm-1 can be assigned to the and C-O, N-H N-H and and O-H N-H O-H bonds;”
Abuhimd 等 - 2020 - Influence of Magnesium Aluminate Nanoparticles on DOI: 10.3390/coatings10100968 -
Alkene (C=C) confidence 1.0
“According to [39] the better asphalt Based on modified binder peak at 1580 cm1 which is binder has the most flexural peaks in the wavenumber aromatics [37] and corresponding to C=C.”
Improving the Temperature Sensitivity of Bitumen for Emergency Pavement Repair DOI: 10.3311/PPci.18351
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