What absorbs at 1519 cm⁻¹ in an FTIR spectrum?
A band near 1519 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 1519 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 |
| Alkene (C=C) | 3 | 3 | 1.0 |
| N-O bond | 2 | 2 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Lignin | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| C=n | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single fixed 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 1519 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=n confidence 1.0
“The bands centered at 1519 and 1454 are assigned to C=N stretching of quinoid and C-N stretching of benzenoid rings, respectively;”
Synthesis of novel conducting polyaniline composites based on seaweed Enteromorpha compressa macro-alga powder DOI: 10.1007/s00289-020-03191-7 -
Aromatic ring confidence 1.0
“t t 1637 1635 1613 1613 1613 1614 rf(ar) Flavonoids, Aromatic stretching t t 1519 1520 1519 1524 1520 1520 rf(ar);”
Discrimination of different genuine Danshen and their extracts by Fourier transform infrared spectroscopy combined with two-dimensional correlation infrared spectroscopy DOI: 10.1016/j.saa.2012.06.013 -
Alkene (C=C) confidence 1.0
“cm-1), intermolecular hydrogen bonds (3398.19 methylene groups (C-H) in phenolic rings (2930.08 cm-1), cm-1), amide I or C=O stretching (1705.62 and 1631.41 amide II or N-H bending and stretching cm-1), cm-1), (1518.75 C=C bending in aromat”
Encapsulation of olive leaf phenolics within electrosprayed whey protein nanoparticles; production and characterization DOI: 10.1016/j.foodhyd.2019.105572 -
Hydroxyl (O-H) confidence 1.0
“In addition, the weak band near 1519 H-O-H assigned to bending vibration mode were presented due to the adsorption of moisture when FTIR sample disks were cm(cid:1)1 prepared in open air [26].”
Synthesis and structural properties of ZnO and diatomite-supported ZnO nanostructures DOI: 10.1016/j.ceramint.2015.09.169 -
Carbonyl (C=O) confidence 1.0
“The band at 1636 cm-1 characterizes the vibration stretching for C=O carbonyl group [58], 1519 cm-1, and 1041 cm-1.”
Ocimum basilicum-Mediated Synthesis of Silver Nanoparticles Induces Innate Immune Responses against Cucumber Mosaic Virus in Squash DOI: 10.3390/plants11202707 -
Amide confidence 1.0
“2nd a component predominantly made up of the amide II fitted Observed vs concentrations of mAbs bound to PrAc resin samples cm-1 cm-1 band shoulder at 1519 and amide III band at 1234 4†) (ESI Fig.”
Beattie 等 - 2021 - Insight into purification of monoclonal antibodies DOI: 10.1039/d1an00985k -
Aromatic ring confidence 1.0
“cm-1 (vi) the peak situated at 1520 is present in the 5-DCB spectrum, but also in the CGA cm-1, spectrum at 1519 and is assigned to a vibration rotation of the phenyl bond [32,33];”
Bita 等 - 2023 - Diester Chlorogenoborate Complex A New Naturally DOI: 10.3390/inorganics11030112 -
N-O bond confidence 1.0
“As 30wt% UF was added in sample F, two new 1149 1114 1629 750 1519cm-1 1236 82.5 peaks that corresponded to N-O were observed at”
Chiang 等 - 2016 - Urea Formaldehyde Composites Reinforced with Sago DOI: 10.1155/2016/5954636
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