What absorbs at 798 cm⁻¹ in an FTIR spectrum?
A band near 798 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 798 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 |
|---|---|---|---|
| Silicon-oxygen (Si-O) | 15 | 15 | 1.0 |
| Siloxane (Si-O-Si) | 7 | 7 | 1.0 |
| Hydroxyl (O-H) | 5 | 5 | 1.0 |
| Silicon (Si) | 4 | 4 | 1.0 |
| Aromatic ring | 3 | 3 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| C-O single bond | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| Ring structure | 2 | 2 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Sulfate (SO4) | 1 | 1 | 1.0 |
| Nitrogen heterocycle | 1 | 1 | 1.0 |
| Metal hydroxyl | 1 | 1 | 1.0 |
| Sulfur | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Metal oxygen | 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 |
|---|---|---|---|
| Nanotubes | 798, 1735, 1630 | Hydroxyl (O-H) | 1 |
| nanotube | 798, 1540, 1080 | Hydroxyl (O-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 798 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
-
confidence 1.0
“The peak at 1076 can cm-1 be clearly observed because of the asymmetrical Si-O-Si stretch and peak at 798 indicating the cm-1 presence of asymmetric vibrations from Si-O-Si.”
Arizka 等 - 2019 - Synthesis and Physical Properties Characterization DOI: 10.1088/1757-899X/546/4/042004 -
Amide confidence 1.0
“For PANI, the peak at 1300 and CEPTE cm-1 798 is related to C-N stretching vibrations, and the out-of-plane bending of C-H [6, 34-36].”
Highly conductive and flexible silk fabric via electrostatic self assemble between reduced graphene oxide and polyaniline DOI: 10.1016/j.orgel.2017.12.016 -
Alkyl C-H confidence 1.0
“The absorption peak at cm-1 798 is attributed to the outward bending vibration of the C-H of the disubstituted benzene ring.”
Jin 等 - 2018 - Polymer anode used in hydrometallurgy Anodic beha DOI: 10.1016/j.hydromet.2018.01.020 -
Sulfur confidence 1.0
“The peak around carbon-oxygen bonds in these structures which is mendisplacement occurred for the one at 798 cm -1 730 cm could be attributed to carbon-sulfur stretching vibration.”
A case study of poly (aryl ether sulfone) hemodialysis membrane interactions with human blood: Molecular dynamics simulation and experimental analyses DOI: 10.1016/j.cmpb.2020.105742 -
confidence 1.0
“1239.2 and 1087.8 Si-OH 953.7 Symmetric Si-O-Si stretching 797.5 Si-O-Si bending 458.1 C-H stretching of trimetylsilyl 2970 - 2850 Si-C stretching 846.7 and 758.9 The intensity of band characteristic of C=O groups for all cases was increase”
Nurul 等 - 2012 - XRD, FTIR and C-13 CPMAS NMR Studies of Composite DOI: 10.4028/www.scientific.net/AMR.364.159 -
Aromatic ring confidence 1.0
“LLM confirmed rule peak-group candidate”
Suneetha 和 Vedhi - 2013 - Synthesis, Characterisation and Voltammetric behav DOI: 10.4028/www.scientific.net/AMR.678.258 -
confidence 1.0
“cm-1 cm-1 The peaks at approximately 1100-1020 and 912 are assigned to stretching at wavenumbers 908 cm-1, 798 cm-1 and 752 cm-1 that can be assigned to the Al-Al-OH, at wavenumbers 908 cm-1, 798 cm-1 and 752 cm-1 that can be assigned to th”
Selectively Etched Halloysite Nanotubes as Performance Booster of Epoxidized Natural Rubber Composites DOI: 10.3390/polym13203536 -
Hydroxyl (O-H) confidence 1.0
“However, greenish yellow faustite is high in V and shows a single peak at 798 with w(V 2O 5)>1.00%, lacking the double peaks from OH bending vibration.”
Wang 和 Guo - 2021 - The impact of trace metal cations and absorbed wat DOI: 10.1098/rsos.201110
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