What absorbs at 1383 cm⁻¹ in an FTIR spectrum?
A band near 1383 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 1383 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 | 16 | 14 | 1.0 |
| Methacrylate | 12 | 11 | 1.0 |
| Acetate | 12 | 11 | 1.0 |
| Methoxy (OCH3) | 9 | 9 | 1.0 |
| C-O single bond | 8 | 8 | 1.0 |
| Carboxyl (COOH) | 8 | 7 | 1.0 |
| Hydroxyl (O-H) | 6 | 6 | 1.0 |
| Methyl | 4 | 4 | 1.0 |
| Water (H2O) | 3 | 3 | 1.0 |
| Ketone | 3 | 2 | 1.0 |
| Ester | 3 | 2 | 1.0 |
| Carbonyl (C=O) | 3 | 2 | 1.0 |
| Amide | 3 | 2 | 1.0 |
| Alkene (C=C) | 3 | 2 | 1.0 |
| Metal oxygen | 2 | 2 | 1.0 |
| Carbonate | 2 | 2 | 1.0 |
| C c single bond | 2 | 2 | 1.0 |
| N-O bond | 1 | 1 | 1.0 |
| Amine primary | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| C=n | 1 | 1 | 1.0 |
| Siloxane (Si-O-Si) | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| Fluorine (C-F) | 1 | 1 | 0.5 |
| Nitrogen heterocycle | 1 | 0 | 1.0 |
| Carbon dioxide | 1 | 0 | 1.0 |
| Anhydride | 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 |
|---|---|---|---|
| PMMA | 1383, 1722, 1628 | Methacrylate, Acetate, Alkyl C-H | 1 |
| Al2O3 | 1383, 1722, 2981 | Methacrylate, Acetate, Alkyl C-H | 1 |
| nanocomposite | 1383, 2921, 3300 | Alkyl C-H, Methacrylate, Acetate | 1 |
| CS | 1383, 1645, 1720 | Methacrylate, Acetate, Alkyl C-H | 1 |
| ZnO NPs | 1383, 1664, 875 | Alkyl C-H, Methacrylate, Acetate | 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 1383 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
-
Alkyl C-H confidence 1.0
“cm-1) cm-1), cm-1).9, 10 CH stretching (954 and C-C vibration (868 -CHbending (754 and 1383 cm-1 The peak at 872 observed in all samples which is due to C-C stretching and featured for cm-1 amorphous properties of films.”
Ghosh 等 - 2020 - Blown films fabrication of poly lactic acid based DOI: 10.1016/j.mtcomm.2019.100737 -
Hydroxyl (O-H) confidence 1.0
“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 aromatic rings of phenolic compounds (1455.77 C-N cm-1), cm-1) stretching groups (1383.22 deformation of O-H”
Encapsulation of olive leaf phenolics within electrosprayed whey protein nanoparticles; production and characterization DOI: 10.1016/j.foodhyd.2019.105572 -
Acetate confidence 1.0
“FTIR spectra (EIS) measurements, the highest ionic conductivity at room temperature is determined as cm-1, cm-1 twisting mode at 1383.43 C=O stretching mode at 1721.56 which proven the interaction analysis showed CH2 cm-1.”
Effect of Al2O3 in poly(methyl methacrylate) composite polymer electrolytes DOI: 10.1063/1.5034559 -
Hydroxyl (O-H) confidence 1.0
“The peak at 1632 cm-1 The band at 1383 is corresponding to bending vibrations of -OH in phenols or symmetric stretching vibration”
Vindhya 等 - 2019 - Dielectric properties of Zinc Oxide Nanoparticles DOI: 10.1063/1.5093888 -
Acetate confidence 1.0
“Strong bands at 1382.96 1230.58 and 1105.21 are cm-1, cm-1, corresponding to C-O stretching vibrations.”
Al-Qahtani 等 - 2022 - Structural, morphological, optical and electrochem DOI: 10.15251/JOR.2022.182.187 -
Hydroxyl (O-H) confidence 1.0
“bending vibrations of the hydroxyl groups (O-H) for the adsorbed water molecules on the Whereas, the bands located at 1383, 1087, and 1047 cm-1 could be attributed to the stretchsamples' surfaces, depending upon the blending of these specim”
Biosynthesis, Physicochemical and Magnetic Properties of Inverse Spinel Nickel Ferrite System DOI: 10.3390/cryst12111542 -
Carboxyl (COOH) confidence 1.0
“At 1584 cm-1 was the stretching vibration ( , asymmetric (v stretching) of in , and the peak at 1383 was attributed to the vibration s, symmetric a COO-”
A Soluble Humic Substance for the Simultaneous Removal of Cadmium and Arsenic from Contaminated Soils DOI: 10.3390/ijerph16244999 -
Acetate confidence 1.0
“the O-C asymmetric mode of the ester groups was observed at appeared at 1383 cm-1, cm-1 1088 and the peaks appeared at 957 and 913 were attributed to the rocking -1, mode of CH 3.”
Boudjema 等 - 2020 - Green composites based on Atriplex halimus fibers DOI: 10.1515/polyeng-2020-0068
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