What absorbs at 870 cm⁻¹ in an FTIR spectrum?
A band near 870 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 870 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 | 10 | 9 | 1.0 |
| Carbonate | 9 | 9 | 1.0 |
| C-O single bond | 7 | 6 | 1.0 |
| Methoxy (OCH3) | 6 | 5 | 1.0 |
| Methacrylate | 6 | 5 | 1.0 |
| Acetate | 6 | 5 | 1.0 |
| Metal oxygen | 4 | 4 | 1.0 |
| Hydroxyl (O-H) | 4 | 2 | 1.0 |
| Phosphate (PO4) | 3 | 3 | 1.0 |
| Aromatic ring | 3 | 3 | 1.0 |
| Silicon-oxygen (Si-O) | 3 | 3 | 1.0 |
| C c single bond | 2 | 2 | 1.0 |
| Oxygen heterocycle | 2 | 2 | 1.0 |
| Silicon (Si) | 2 | 2 | 1.0 |
| Carbohydrate | 2 | 2 | 1.0 |
| Silicate | 1 | 1 | 1.0 |
| Nucleic acid | 1 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| C-S single bond | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Silanol (Si-OH) | 1 | 1 | 1.0 |
| Silicon hydride | 1 | 1 | 1.0 |
| Silicon carbon | 1 | 1 | 1.0 |
| Fluorine (C-F) | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Alkene (C=C) | 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 |
|---|---|---|---|
| ZnO | 870, 1400, 3430 | Alkyl C-H, C-O single bond, Methoxy (OCH3) | 2 |
| SiC | 870, 791, 805 | Alkyl C-H | 1 |
| PVC | 870, 834, 1195 | Alkyl C-H, Methoxy (OCH3), C-O single bond | 1 |
| PVDF | 870, 1160, 840 | 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 870 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
-
Alkyl C-H confidence 1.0
“The thermogram indicated C-H stretching while the bands at 870 and cm-1 the thermostability of the gum to high 770 indicated the C-H bending.”
Bamigbola 等 - 2018 - Isolation and Characterization of Cola acuminata G DOI: 10.9734/JPRI/2018/14526 -
Acetate confidence 1.0
“In contrast, the slow C pool refl ects the mid-range stability as (C-O stretch of cellulose), and 870 (aromatic C-H and C=C).”
Calderon 等 - 2011 - Chemical Differences in Soil Organic Matter Fracti DOI: 10.2136/sssaj2009.0375 -
Alkyl C-H confidence 1.0
“700-900 liptinite, semifusinite, and fusinite from several representative coal out-of-plane deformation at In addition, inertinite Table4 cm-1bandsinthearomatic Evolutionoftheintegratedpeakareasof870,815,and715 C-H out-of-plane deformation”
Chen 等 - 2012 - Characterization of chemical functional groups in DOI: 10.1016/j.coal.2012.09.001 -
Amide confidence 1.0
“cm-1, cm-1, There were three primary peak absorptions on the wavelengths ranged from 400-515 870 cm-1 and 1250 showing that the ZnO absorption was identified on the wavelengths ranged from 400cm-1, 515 while the absorption of H-C-N function”
Idiawati 等 - 2017 - Effect of Growth Time on the Characteristics of Zn DOI: 10.1088/1757-899X/202/1/012050 -
Alkyl C-H confidence 1.0
“Table4 Peakareasforreflectancemicro-FTIRspectra.AR1=areaof3100-3000cm-1/areaof3000-2800cm-1.AR2=areaof900-700cm-1/areaof3000-2800cm-1.%2960=areaofband centeredat2960cm-1/areaof3000-2800cm-1.%2920=areaofbandcenteredat2920cm-1/areaof3000-2800”
Geochemical and petrographic alteration of rapidly heated coals from the Herrin (No. 6) Coal Seam, Illinois Basin DOI: 10.1016/j.coal.2016.08.022 -
C c single bond confidence 1.0
“Asymmetrical stretching vibrations of C-C-C and C-F stretching vibrations were attributed to cm-1 cm-1, the bands at 870 and 842 respectively [24].”
Ramadan 和 Ismail - 2022 - Tunning the Physical Properties of PVDFPVCZinc F DOI: 10.21203/rs.3.rs-935328/v1 -
Alkyl C-H confidence 1.0
“The intense peak at 870 tial oils to acts as stabilizing and reducing agents for biosynthesis of CuO ˭C-H attributed to the vibration due to their presence of alkene funcNPs from copper sulfate.”
Green chemistry route of biosynthesized copper oxide nanoparticles using Psidium guajava leaf extract and their antibacterial activity and effective removal of industrial dyes DOI: 10.1016/j.jece.2021.105033 -
Silicon carbon confidence 1.0
“10001C, annealed at the FWHM of the (002) ZnO peak is films have a great relation with the condition of the SiC 0.191 only which is much smaller than those without SiC buffer layer due to the hetero-interfaces being very sensitive 891cm(cid”
Sha 等 - 2006 - Initial study on the structure and optical propert DOI: 10.1016/j.physe.2006.03.138
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