What absorbs at 920 cm⁻¹ in an FTIR spectrum?
A band near 920 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 920 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 | 8 | 7 | 1.0 |
| Hydroxyl (O-H) | 5 | 5 | 1.0 |
| Phosphate (PO4) | 4 | 4 | 1.0 |
| Methoxy (OCH3) | 4 | 4 | 1.0 |
| Methacrylate | 4 | 4 | 1.0 |
| C-O single bond | 4 | 4 | 1.0 |
| Acetate | 4 | 4 | 1.0 |
| Silicon-oxygen (Si-O) | 4 | 4 | 1.0 |
| Carboxyl (COOH) | 3 | 3 | 1.0 |
| Metal hydroxyl | 3 | 3 | 1.0 |
| Alkene (C=C) | 2 | 2 | 1.0 |
| Carbohydrate | 2 | 2 | 1.0 |
| Oxygen heterocycle | 2 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Nucleic acid | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Siloxane (Si-O-Si) | 1 | 1 | 1.0 |
| Metal oxygen | 1 | 1 | 1.0 |
| C=n | 1 | 1 | 0.9 |
| Ring structure | 1 | 0 | 1.0 |
| Nitrogen heterocycle | 1 | 0 | 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 |
|---|---|---|---|
| copper oxide | 920, 624, 1686 | Hydroxyl (O-H), Alkyl C-H | 1 |
| copper oxide nanoparticles | 920, 624, 1317 | Hydroxyl (O-H), 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 920 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
-
Metal hydroxyl confidence 1.0
“data.33-35 cm-1 The shoulder at 831 is due to the stretching cm-1 Al-O mode, whereas the band near 920 is tentatively Al-OH Alassigned as a mixed modes arising from stretch, O-Al Si-O-Si Si-O-Al vibration, and and stretching”
Fali 等 - 2021 - Nanoscale Spectroscopy of Dielectric Properties of DOI: 10.1021/acsphotonics.0c00951 -
Hydroxyl (O-H) confidence 1.0
“cm-1 of the OH deformation band of Bco_dried at 920 into The fluoride element was detected in the sample Bco_ three others components for Pca4_dried at 938;”
Thermal, morphostructural and spectrometric characterization of an antibacterial kaolinite-based filter modified with silver for water treatment DOI: 10.1007/s10973-020-09267-w -
Metal oxygen confidence 1.0
“dothermic peak at 920(cid:3)C and an exothermic peak at air-annealed samples of copper oxide nanoparticles 935(cid:3)C.”
Kayani 等 - 2015 - Characterization of Copper Oxide Nanoparticles Fab DOI: 10.1007/s11664-015-3867-5 -
Alkyl C-H confidence 1.0
“In cm-1generally 920 this paper, an absorption at about 2 attributed to aliphatic C-H group stretching (Vergnoux kg-1 for O.”
Li 和 Wu - 2013 - Compositional and Structural Difference of Fulvic DOI: 10.1016/S2095-3119(13)60397-4 -
Carbohydrate confidence 1.0
“Evidently, the presence of cm(cid:2)1, region I, i.e., the simultaneous presence of three peaks at 920, 1,020, and 1,100 is attributed to glycogen (41).”
Maddela 等 - 2018 - Functional Determinants of Extracellular Polymeric DOI: 10.1128/AEM.00756-18 -
Alkyl C-H confidence 1.0
“cm-1, cm-1, cm-1 1279 471 1239 1138 1050 were obtained for ODS cake for which the cm-1, cm-1, cm-1, cm-1, cm-1, 991 probable assignments are O-H, C-H expansion vibration920 866 850 682 cm-1 cm-1were unsaturated oil/linoleic acid, C-H, C-H (”
Functional and structural characteristics of chocolate flavoured cake incorporated with surimi powder from Nemipterus species DOI: 10.1007/s13197-020-04914-4 -
Acetate confidence 1.0
“1164 C-O (sp3) stretching 920 973 C-H deformation (aromatic) [out of plane] 859”
Yusoff 等 - 2018 - Theoretical and Experimental Approach Towards P-Cy DOI: 10.1088/1757-899X/374/1/012086 -
Hydroxyl (O-H) confidence 1.0
“The main intention The maximum sharp absorption band at is a charof this work is to analyse the spectral signature obtained by vibraacteristic of Si-O-Fe and Si-O-Si stretching vibration, which plays tional spectrometry, and compare the res”
do Nascimento-Dias 等 - 2020 - Detection of organic or inorganic material in Mart DOI: 10.1017/S147355042000021X
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