What absorbs at 696 cm⁻¹ in an FTIR spectrum?
A band near 696 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 696 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 | 5 | 5 | 1.0 |
| Aromatic ring | 3 | 3 | 1.0 |
| N h | 2 | 2 | 1.0 |
| Sulfate (SO4) | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| Metal oxygen | 1 | 1 | 1.0 |
| Amine primary | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| Styrene | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Fluorine (C-F) | 1 | 1 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Metal halide | 1 | 1 | 0.9 |
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 |
|---|---|---|---|
| polystyrene | 696, 1020, 1600 | Aromatic ring, Alkyl C-H | 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 696 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
-
Carbohydrate confidence 1.0
“798cm(cid:3)1, 780cm(cid:3)1 693cm(cid:3)1 and that were assigned for type 3 cm(cid:3)1 two nearly similar intensity peaks in M23/08 at 696 and a-polysaccharide band of [20].”
Choong 等 - 2014 - Identification of geographical origin of Lignosus DOI: 10.1016/j.molstruc.2014.04.001 -
C-O single bond confidence 1.0
“The cm-1 band at 1504 is attributed to the phenyl nucleus stretching of BPEBPA and the absorption bands at 696 Methods ≡C-H cm-1 are attributed to the deforma(cid:2) and 1173 tion and the ether linkage present in the BPEBPA, The FTIR spectr”
Surender 等 - 2014 - Bismaleimide and Bispropargyl Ether Blends Curing DOI: 10.1134/S1560090414050157 -
Alkyl C-H confidence 1.0
“The pronounced peak at 1446.41 is assigned to the can be observed at 754.61 and 695.93 cm-1, while the out-of-plane deformation of the phethe CH group bending vibration.”
Modeling and Simulation of Fabricated Graphene Nanoplates/Polystyrene Nanofibrous Membrane for DCMD DOI: 10.3390/polym13172987 -
confidence 1.0
“(O corresponds to oxygen from the corner of the heteropolyanion structure), W-O e-W c IR spectrum of PDPA doped with the PTA heteropolyanions is characterized by the IR (O corresponds to oxygen from the side of the heteropolyanion structure”
The Photoluminescence and Vibrational Properties of Black Phosphorous Sheets Chemically/Electrochemically Functionalized in the Presence of Diphenylamine DOI: 10.3390/polym14214479 -
Fluorine (C-F) confidence 1.0
“The presence of the fluoroalkyl groups was proved by cm-1 the bands at 1241 and 1206 that are attributed to the C-F stretching, and the weak cm-1 band at 696 ascribed to the CF2 scissoring [35].”
Bellido-Aguilar 等 - 2019 - Effect of a fluoroalkyl-functional curing agent on DOI: 10.1016/j.surfcoat.2019.02.006 -
Alkyl C-H confidence 1.0
“structure;1:2:4substitutedphenylring Houttoplanedeviationalvibrations 834 C H 754 VibrationofaromaticC Sbond 696 C H 545 BendingofC S Ostretchingvibrations 1176;1109;1027 O”
Electrochimica Acta Sulfonated polyphenyl ether by electropolymerization DOI: 10.1016/j.electacta.2012.07.082 -
Aromatic ring confidence 1.0
“Furthermore, the peak at 1720 originates from the carbonyl stretch, cm-1 whereas the peak around 696 results from the aromatic ring bending.”
Influence of Waste Toner on Asphalt Binder: Chemical and Rheological Characterization DOI: 10.3390/molecules28062794 -
Aromatic ring confidence 1.0
“After modification with styrene, a new absorption peak Polymers2022,14,786 5of13 appeared at 696 cm-1 due to the phenyl group of styrene.”
Jambrekovic 等 - 2022 - Viscoelastic and Thermal Properties of Styrene Mod DOI: 10.3390/polym14040786
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