What absorbs at 1536 cm⁻¹ in an FTIR spectrum?
A band near 1536 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 1536 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 | 7 | 7 | 1.0 |
| Alkyl C-H | 5 | 5 | 1.0 |
| Secondary amine | 4 | 4 | 1.0 |
| N h | 4 | 4 | 1.0 |
| Carboxyl (COOH) | 4 | 4 | 1.0 |
| Aromatic ring | 4 | 3 | 1.0 |
| Carbonyl (C=O) | 3 | 3 | 1.0 |
| C n single bond | 2 | 2 | 1.0 |
| Alkene (C=C) | 2 | 2 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Ester | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| C c single bond | 2 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Urethane | 1 | 1 | 1.0 |
| Ammonium | 1 | 1 | 1.0 |
| Nitro (NO2) | 1 | 1 | 0.7 |
| Nitrogen heterocycle | 1 | 0 | 1.0 |
| 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 |
|---|---|---|---|
| nanocellulose | 1536, 1540, 1646 | Alkyl C-H, Amide | 1 |
| cellulose | 1536, 1735, 1650 | Alkyl C-H, Amide | 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 1536 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
-
Amide confidence 1.0
“Amide II bands appear ~ 1536 CH asymmetric stretching vibration by 25% and 56% were”
Spectral profile index changes as biomarker of toxicity in Catla catla (Hamilton, 1822) edible fish studied using FTIR and principle component analysis DOI: 10.1007/s42452-020-3001-z -
Acetate confidence 1.0
“The reduced C=O and C=C peaks at 1734 cm-1 and 1536 cm-1, respectively, in the Fourier-transform Infrared (FTIR) spectra of isolated NC, confirmed the removal of appreciable amounts of hemicellulose and lignin components in the OPL fibers.”
Shunmugam 等 - 2021 - TAGUCHI ORTHOGONAL DESIGN FOR OPTIMIZING A UNIFIED DOI: 10.11113/jurnalteknologi.v83.15109 -
Alkyl C-H confidence 1.0
“From this data, it can be seen that the MAPP spectrum contains peaks at 2916, 2855 and 1536 cm-1, which is specifically attributed to the characteristic stretching absorption peaks of -CH2-CH2and NH3+ ions.”
Abuhimd 等 - 2020 - Influence of Magnesium Aluminate Nanoparticles on DOI: 10.3390/coatings10100968 -
Alkyl C-H confidence 1.0
“Peaks at 1536 cm-1 correspond to C-H bending (aromatic compounds) or C=C=C stretching (alkene).”
Characterizations of Alpha-Cellulose and Microcrystalline Cellulose Isolated from Cocoa Pod Husk as a Potential Pharmaceutical Excipient DOI: 10.3390/ma15175992 -
N h confidence 1.0
“On the other cm-1 hand, the absorption at 1536 is attributed to the bending deformations related to the NH group of the formed urethane bond [32].”
Synthesis and Characterizations of Eco-Friendly Organosolv Lignin-Based Polyurethane Coating Films for the Coating Industry DOI: 10.3390/polym14030416 -
C c single bond confidence 1.0
“are denoted in the cm-1 P2 FTIR spectrum by the 3056 band (P2) specific to (ar)C-C groups [21] and the cm-1 1536 band specific to the skeletal vibrations of the aromatic bonds, C=C, reported in cm-1-1550 cm-1 literature as being in the rang”
The Origin and Physico-Chemical Properties of Some Unusual Earth Rock Fragments DOI: 10.3390/app12030983 -
Amide confidence 1.0
“05 amide II, which originates from N-H deformation, shifts 1536cm-1.”
Dyakonov 等 - 2012 - Design and characterization of a silk-fibroin-base DOI: 10.1155/2012/490514 -
Carboxyl (COOH) confidence 1.0
“LLM confirmed rule peak-group candidate”
An infrared spectroscopic study of the nature of zinc carboxylates in oil paintings DOI: 10.1039/c5ja00120j
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