What absorbs at 1632 cm⁻¹ in an FTIR spectrum?
A band near 1632 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 1632 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 | 30 | 29 | 1.0 |
| Carbonyl (C=O) | 19 | 18 | 1.0 |
| Hydroxyl (O-H) | 16 | 14 | 1.0 |
| Methacrylate | 14 | 14 | 1.0 |
| Acetate | 14 | 14 | 1.0 |
| Carboxyl (COOH) | 13 | 13 | 1.0 |
| Water (H2O) | 13 | 11 | 1.0 |
| Ketone | 12 | 12 | 1.0 |
| Ester | 11 | 11 | 1.0 |
| N h | 10 | 10 | 1.0 |
| Alkene (C=C) | 8 | 7 | 1.0 |
| Protein beta sheet | 6 | 6 | 1.0 |
| C-O single bond | 5 | 5 | 1.0 |
| Secondary amine | 5 | 5 | 1.0 |
| Aromatic ring | 4 | 4 | 1.0 |
| Methoxy (OCH3) | 4 | 4 | 1.0 |
| Carbohydrate | 2 | 2 | 1.0 |
| C n single bond | 2 | 2 | 1.0 |
| C c single bond | 2 | 2 | 1.0 |
| Protein alpha helix | 2 | 2 | 1.0 |
| Ring structure | 2 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Protein random coil | 1 | 1 | 1.0 |
| Siloxane (Si-O-Si) | 1 | 1 | 1.0 |
| Metal oxygen | 1 | 1 | 1.0 |
| C=n | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
| Lignin | 1 | 1 | 1.0 |
| Carbonate | 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 1632 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
“The transport mechanism of showed amide I and II absorption peaks at 1632 and 1554 19 cm@1, hydrogels was a combination of non-Fickian and Super Case II.”
Arikibe 等 - 2019 - pH-Responsive Studies of Bacterial CelluloseChito DOI: 10.1002/slct.201902290 -
Water (H2O) confidence 1.0
“(mol%) cm(cid:0) 1 (vi) The intense peak at 1632 is related to vibrations of water,”
Preparation and characterization of invert ZnOâ B2O3 glasses and its shielding behavior towards gamma irradiation DOI: 10.1016/j.matchemphys.2019.122129 -
Carbonyl (C=O) confidence 1.0
“cm-1 cm-1 The vibration 1648 is accompanied by the vibration ~1632 (which is assigned S to the carbonyl stretching in amid I - -pleated sheet components of proteins) [31].”
Fourier transform infrared microspectroscopy detects biochemical changes during C. elegans lifespan DOI: 10.1016/j.vibspec.2019.04.005 -
Hydroxyl (O-H) confidence 1.0
“-1 corresponding to vibration bands of CS-nZVI in the range of 40 0 - 40 0 0 cm .The broad and intense -1 -1 -H peak around 3394 cm correspond to the presence of O stretching from alcohol, 1632 cm is -1 -O -H attributed to H bending, the pe”
Bottom-up approach synthesis of core-shell nanoscale zerovalent iron (CS-nZVI): Physicochemical and spectroscopic characterization with Cu(II) ions adsorption application DOI: 10.1016/j.mex.2020.100976 -
Acetate confidence 1.0
“Thus, it will be interesting to study the represents the C=O stretching vibration of I at 1632 cr/I and FWHM dependence of crystalline index factor on I hemicellulose and lignin.”
Das 等 - 2017 - Extraction of xylem fibers from Musa sapientum and DOI: 10.1007/s12221-017-1187-5 -
Amide confidence 1.0
“The bands in the 1632 bladders of biologically synthesized CuO-NPs oral in biogenic method could be related to amides (N-H) filled gavaged mice were with reddish yellow urine.”
El Bialy 等 - 2020 - Comparative Toxicological Effects of Biologically DOI: 10.2147/IJN.S241922 -
Water (H2O) confidence 1.0
“The characteristic IR peaks located at 1632 could be assigned to δ (H 2O) cm-1 bending vibrations from the residual absorbed water and 1405 can be assigned to the ((cid:1) ((cid:1) asymmetric as) and symmetric as) bending vibrations of δ (O”
Gaurkhede 等 - 2012 - Effect of Rare Earth Doped Elements and Characteri DOI: 10.4028/www.scientific.net/AMR.585.174 -
C c single bond confidence 1.0
“The energy disphosphate 1255 and 1077 respectively belong to the stretch1632, X-ray spectroscopy (EDS) was done as a complement to persive ing vibration of carbonyl, C C, C OH and C O [33,44,45].”
Phosphorization of exfoliated graphite for developing flame retardant ethylene vinyl acetate composites DOI: 10.1016/j.jmrt.2020.04.085
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