What absorbs at 1636 cm⁻¹ in an FTIR spectrum?
A band near 1636 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 1636 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 | 34 | 31 | 1.0 |
| Carbonyl (C=O) | 28 | 26 | 1.0 |
| Carboxyl (COOH) | 27 | 24 | 1.0 |
| Methacrylate | 23 | 22 | 1.0 |
| Acetate | 23 | 22 | 1.0 |
| Water (H2O) | 20 | 20 | 1.0 |
| Hydroxyl (O-H) | 19 | 18 | 1.0 |
| Alkene (C=C) | 17 | 17 | 1.0 |
| Ketone | 17 | 16 | 1.0 |
| Ester | 17 | 16 | 1.0 |
| Alkyl C-H | 16 | 16 | 1.0 |
| N h | 13 | 13 | 1.0 |
| Protein | 8 | 8 | 1.0 |
| C-O single bond | 7 | 7 | 1.0 |
| Protein beta sheet | 7 | 5 | 1.0 |
| Methoxy (OCH3) | 6 | 6 | 1.0 |
| Secondary amine | 6 | 6 | 1.0 |
| Aromatic ring | 4 | 4 | 1.0 |
| C n single bond | 4 | 4 | 1.0 |
| Carbohydrate | 3 | 3 | 1.0 |
| Hydrogen bond | 2 | 2 | 1.0 |
| N-O bond | 2 | 2 | 1.0 |
| Carbonate | 2 | 2 | 1.0 |
| C=n | 1 | 1 | 1.0 |
| Sulfonate | 1 | 1 | 1.0 |
| Amine primary | 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 |
| Protein alpha helix | 1 | 1 | 1.0 |
| Phosphorus | 1 | 1 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Metal oxygen | 1 | 1 | 1.0 |
| Phenolic | 1 | 1 | 0.9 |
| Nitrate | 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 |
|---|---|---|---|
| zinc oxide | 1636, 1627, 1638 | Methacrylate, Carboxyl (COOH), Amide | 1 |
| TiO2 | 1636, 1700, 1093 | Methacrylate, Carboxyl (COOH) | 1 |
| zinc oxide nanoparticles | 1636, 1744, 1627 | Methacrylate, Carboxyl (COOH), Amide | 1 |
| silver nanoparticles (AgNPs) | 1636, 1100, 1749 | Amide, Methacrylate, Carbonyl (C=O) | 1 |
| TiO2 nanoparticles | 1636, 1700, 455 | Methacrylate | 1 |
| honey | 1636, 2005, 1199 | Methacrylate, 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 1636 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
-
Hydroxyl (O-H) confidence 1.0
“Earlier studies have established cm-1, cm-1, cm-1, of tea extracts containing polyphenols have appeared at 3388 1636 and 1039 which that the FTIR bands of tea extracts containing polyphenols have appeared at 3388 cm-1, 1636 cm-1, are referr”
Aziz 等 - 2017 - From Insulating PMMA Polymer to Conjugated Double DOI: 10.3390/polym9110626 -
N-O bond confidence 1.0
“lysation reaction of to cm(cid:1)1 C¼¼C The sharp peak at 1636 indicates the bond of the synthesized difunctional monomer and no unreacted materials like 3-MPTS and acrylic acid.”
Synthesis of UV-curable difunctional silane monomer based on 3-methacryloxy propyl trimethoxysilane (3-MPTS) and its UV-curing characteristics and thermal stability DOI: 10.1002/app.31266 -
Carbonyl (C=O) confidence 1.0
“The 1635.78cm-1 C]O peak of shows carbonyl group and 3.5 1411.89cm-1 C-C shows stretching.”
Bawazeer 等 - 2021 - Green synthesis of silver nanoparticles using Trop DOI: 10.1515/gps-2021-0003 -
Alkyl C-H confidence 1.0
“(3000-2800cm(cid:3)1) C-H and The band with a peak point at was responsible for stretching 1636cm(cid:3)1 corresponded to the Amide I and can be of carboxylic acids and NH stretching band of free”
Cebi 等 - 2020 - An evaluation of FTIR spectroscopy for prediction DOI: 10.1080/00218839.2019.1707009 -
Metal oxygen confidence 1.0
“And the peaks that appeared at 1632.68 & 2 cm-1 cm-1 cm-1 619.39 & 660.93 assigned to O-Ti-O stretching 1636.39 corresponds to medium alkane stretch (C=C),”
Biosynthesis of TiO2 nanoparticles by Acalypha indica; photocatalytic degradation of methylene blue DOI: 10.1007/s13204-021-01761-3 -
Carbohydrate confidence 1.0
“The variation in the peaks at 1631, 1547 and 1147 cm-1 WDG formulation from the peaks at 1636, 1534 and 1075 in Bt technical can be attributed to starch and guar gum in the formulation.”
Development of a water dispersible granule (WDG) formulation of Bacillus thuringiensis for the manag DOI: 10.1080/09583157.2021.1895073 -
Aromatic ring confidence 1.0
“Thus, from the cm-1 tal vibrations of the aromatic rings show band 1636 IR spectrum it is evident that the biomolecules present in which is assigned to C = C stretching vibrations which | M.Dhayalanetal.”
Dhayalan 等 - 2021 - Eco friendly synthesis and characterization of zin DOI: 10.1515/nanofab-2020-0104 -
Alkyl C-H confidence 1.0
“Regarding the above, API exhibit a strong band at1636cm-1,characteristicofβ-sheetstructures(Aceitunoappropriate to the C-H stretching vibration, and an N-H cm-1 et al., bond strain vibration band at 3280 belonging to the Medina 2013).”
Garcia-de la Rosa 等 - 2023 - Rheological and structural properties of complex c DOI: 10.24275/rmiq/Alim3003
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