What absorbs at 755 cm⁻¹ in an FTIR spectrum?
A band near 755 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 755 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 |
|---|---|---|---|
| Metal oxygen | 3 | 3 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Alkyl C-H | 2 | 1 | 1.0 |
| Chitosan | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Metal hydroxyl | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 0.9 |
| N h | 1 | 0 | 1.0 |
| C c single bond | 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 |
|---|---|---|---|
| chitosan | 755, 1650, 1655 | Alkyl C-H, Hydroxyl (O-H) | 1 |
| microplastics | 755, 1643, 1614 | Alkyl C-H, 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 755 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
-
Aromatic ring confidence 1.0
“The characteristic peaks at 754.61 and 695.93 and 2 cm-1 543 are assigned to the phenyl ring's CH out-of-plane bending vibrations and CH”
Abdullah 等 - 2021 - Experimental Investigation of Fabricated Graphene DOI: 10.3390/polym13203499 -
confidence 1.0
“In the spectrum obtained for pristine alumina, the following bands characteristic for this compound appear: the O-H stretching band in the wavelength range of 3600-3200 cm-1, the O-H bending oscillation band originating from the water physi”
Klapiszewska 等 - 2019 - Production of cement composites using alumina-lign DOI: 10.5277/ppmp19058 -
Alkene (C=C) confidence 1.0
“the C=C stretching vibration of chitosan ascorbate and the bending vibration of chitosan cm-1, cm-1 3+ -NH is observed at about 1579 and the weak peaks at 755 are attributed to the C=C bending vibration of chitosan ascorbate.”
Investigation of Surface Properties and Free Volumes of Chitosan-Based Buccal Mucoadhesive Drug Delivery Films Containing Ascorbic Acid DOI: 10.3390/pharmaceutics14020345 -
confidence 1.0
“represents the stretching vibrations of Fe-O bond which (747.36cm-1 754.92cm-1) shows slight deviations and due 4.3.”
Nadeem 等 - 2022 - Stability Analysis of Fe3O4-OA-MWCNT Nanocomposite DOI: 10.1155/2022/1859698 -
confidence 1.0
“The stronger broad band at ~3800cm-1 cm-1 3000 and the signal at the 1635-1350 region correspond to bonded OH groups cm-1 vibrations, while the bands at 755 and 590 are assigned to the Al-O vibration of alumina.[22] The difference between t”
Deactivation Study of Ru‐Sn‐B/Al2O3 Catalysts During Selective Hydrogenation of Methyl Oleate to Fatty Alcohol DOI: 10.1002/cjce.23444 -
Silicon-oxygen (Si-O) confidence 0.9
“assigned to Si-O-Al”
Effects of graphene oxide on the geopolymerization mechanism determined by quenching the reaction at intermediate states DOI: 10.1039/c6ra26340b -
confidence 0.8
“Bands at 700 and 755 cm-1 typical of C-S-C groups in vulcanised rubbers.”
Pollution from Transport: Detection of Tyre Particles in Environmental Samples DOI: 10.3390/en15082816 -
confidence 0.7
“Absorption at 755 cm-1 indicates a-glucopyranoside units.”
Karim 和 Islam - 2011 - Thermal Behavior with Mechanical Property of Fluor DOI: 10.1155/2011/979458
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