What absorbs at 856 cm⁻¹ in an FTIR spectrum?
A band near 856 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 856 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 | 3 | 3 | 1.0 |
| Methacrylate | 3 | 3 | 1.0 |
| Acetate | 3 | 3 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| C-O single bond | 2 | 2 | 1.0 |
| Hydroxyl (O-H) | 2 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Carbonate | 1 | 1 | 1.0 |
| Oxygen heterocycle | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Lignin | 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 |
|---|---|---|---|
| PVA | 856, 1660, 2930 | Alkyl C-H, Acetate, Methacrylate | 1 |
| MWCNT | 856, 2876, 1430 | Alkyl C-H, Methoxy (OCH3), Methacrylate | 1 |
| Cellulose | 856, 1735, 1650 | Alkyl C-H, Acetate, Methacrylate | 1 |
| lignin | 856, 1035, 1510 | Alkyl C-H, Methacrylate, Acetate | 1 |
| poly(vinyl alcohol) | 856, 1700, 2993 | Acetate, Methacrylate, Alkyl C-H | 1 |
| CeO2 | 856, 1554, 1630 | Acetate, Methacrylate, Methoxy (OCH3) | 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 856 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
-
C c single bond confidence 1.0
“4 (a)] showed features spectrum band at 2946.67 1 cm-1 (stretching vibration of C-H from alkyl group), 1142.72 ( C-O stretching vibration, 1436.69 cm-1 cm-1 cm-1 (-CH 2stretching), 855.72 (C-C stretching) and the absorption band at 3631.72”
Sprayed in-situ synthesis of Polyvinyl alcohol/Chitosan loaded Silver nanocomposite hydrogel for improved antibacterial effects DOI: 10.1016/j.ijbiomac.2019.09.186 -
Oxygen heterocycle confidence 1.0
“Pure epoxy resin showed peaks near 856 which might be due to oxirane functionality of the epoxidized novolac resin.”
Srivastava 等 - 2018 - Studies on the structural changes during curing of DOI: 10.1016/j.saa.2017.06.066 -
Carbonate confidence 1.0
“In addition, characteristic bands of bidentate carbonates can be visualized at 1576, 1290, 1013, and 856 cm-1, corresponding to the stretching modes υas (CO3) for the first two bands, υs (CO3) for the following, and π (CO3) for the last [88”
CO2 Methanation over Nickel Catalysts: Support Effects Investigated through Specific Activity and Operando IR Spectroscopy Measurements DOI: 10.3390/catal13020448 -
Alkyl C-H confidence 1.0
“for example, Figure single aryl CH vibration was observed at 856 for lignin g-h °C, shows foams fabricated at 300, 500, 700, and 900 and but was not observed for WS or SBP (Figure 4a,d).”
Gupta 等 - 2020 - On the Design of Novel Biofoams Using Lignin, Whea DOI: 10.1021/acsomega.0c00721 -
Acetate confidence 1.0
“The absorbance bands around 856, 930, 996, 1077, 1149, cm-1 and 1242 were related to the C-O stretching, C-H rocking vibrations, and C-O-C”
Extraction and Characterization of Potential Biodegradable Materials Based on Dioscorea hispida Tubers DOI: 10.3390/polym13040584 -
confidence 1.0
“Figure 6e,f present Ni 2p XPS spectra, revealing the existence of peaks at binding energies 855.5 eV and 873.4 eV representing Ni 2p and Ni 2p 1/2, respectively, and the separating energy is”
Nickel Oxide-Carbon Soot-Cellulose Acetate Nanocomposite for the Detection of Mesitylene Vapour: Investigating the Sensing Mechanism Using an LCR Meter Coupled to an FTIR Spectrometer DOI: 10.3390/nano -
confidence 1.0
“The Ni2p spectrum displays a main peak at 856.1 eV attributed to Ni(OH) 2.”
Synthesis of NiFeOx nanocatalysts from metal–organic precursors for the oxygen evolution reaction DOI: 10.1039/D2DT01370C -
confidence 1.0
“Peaks at 855.65 and 872.90 eV indicates to Ni 2p3/2 2p1/2 and Ni energy levels, respectively.”
Ni(OH)2-decorated nitrogen doped MWCNT nanosheets as an efficient electrode for high performance supercapacitors DOI: 10.1038/s41598-019-42281-z
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