What absorbs at 1323 cm⁻¹ in an FTIR spectrum?
A band near 1323 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 1323 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 | 9 | 8 | 1.0 |
| Hydroxyl (O-H) | 4 | 3 | 1.0 |
| Methacrylate | 3 | 3 | 1.0 |
| Acetate | 3 | 3 | 1.0 |
| N h | 3 | 3 | 1.0 |
| Carboxyl (COOH) | 3 | 2 | 1.0 |
| Ring structure | 2 | 2 | 1.0 |
| Aromatic ring | 2 | 2 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| Chlorine | 2 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| N eq o | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Nitro (NO2) | 1 | 1 | 1.0 |
| S eq o | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 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 |
|---|---|---|---|
| graphene | 1323, 1720, 2097 | Methacrylate, Acetate, Hydroxyl (O-H) | 1 |
| silver nanoparticles | 1323, 1636, 1631 | Hydroxyl (O-H), Alkyl C-H, Methacrylate | 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 1323 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
-
Acetate confidence 1.0
“ACCEPTED MANUSCRIPT cm-1 while the band at 1323.28 is assigned to symmetric vibration of -C-O functionality of cm-1 alcohol, ether or carboxylic acid.”
Haq 等 - 2018 - Fabrication of pure and moxifloxacin functionalize DOI: 10.1016/j.jphotobiol.2018.07.011 -
Alkyl C-H confidence 1.0
“Other less intense bands that are located at 1485, 1323cm-1 1447, 1402, 1348 and could be associated to the inplane C-H bending vibrations of the benzene ring that interacts (sometimes strongly) with various ring CC vibrations [18].”
Moros 等 - 2007 - Quality control Fourier transform infrared determi DOI: 10.1016/j.jpba.2006.10.036 -
N h confidence 1.0
“The FTIR of LX (pure drug) shown intense bands at 3060 cm-1, 1647 cm-1, 1590 cm-1, cm-1, cm-1 1590 1323 and 783 corresponding to the functional groups NH, C=O, cm-1, 1323 cm-1, and 783 cm-1 corresponding to the functional groups NH, C=O, CO”
Almotairi 等 - 2022 - Design and Optimization of Lornoxicam Dispersible DOI: 10.3390/ph15121463 -
Nitro (NO2) confidence 1.0
“The peak at 1323 may occur due to the bending vibration of nitro groups”
Eucalyptus globulus and Salvia officinalis Extracts Mediated Green Synthesis of Silver Nanoparticles and Their Application as an Antioxidant and Antimicrobial Agent DOI: 10.3390/plants11081085 -
Alkyl C-H confidence 1.0
“1323 2 and CH stretching modes, whereas the small absorption bands Finally, it is noteworthy that, whereas in the visible images, a”
Chiappe 等 - 2019 - Combined Use of Scanning Electron Microscopy-Energ DOI: 10.1021/acsomega.9b03145 -
confidence 1.0
“(bending)/-CH 2203 CH (symmetric stretching) 2 2 stretching)/N-H 1323 CO (stretching) + CCH (stretching) + ring of pyranose (antisymmetric (bending) stretching)/C-O 1255 CO (stretching) + CCH (stretching) + ring of pyranose (antisymmetric (”
Hayyan 等 - 2015 - Functionalization of graphene using deep eutectic DOI: 10.1186/s11671-015-1004-2 -
Alkyl C-H confidence 1.0
“cm´1 the band at 991 corresponds to C-H out of plane deformation vibrations, and the peaks at 1456 C-N vibrations, the band at 991 cm-1 corresponds to C-H out of plane deformation vibrations, and cm´1 (δ (δ and 1323 relate to asymmetrical C”
Magina 等 - 2016 - High Pressure Laminates with Antimicrobial Propert DOI: 10.3390/ma9020100 -
Alkyl C-H confidence 1.0
“and 1321 cm-1 vanishes from the polymer spectrum because, due to polymerization, CH 2= reaction and formation of aliphatic structure occur, leaving only a band at 1323 cm-1 related to CH deformation vibrations in the δ(CH 3) plane.”
Influence of Dimethacrylate Monomer on the Polymerization Efficacy of Resin-Based Dental Cements—FTIR Analysis DOI: 10.3390/polym14020247
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