What absorbs at 864 cm⁻¹ in an FTIR spectrum?
A band near 864 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 864 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 |
|---|---|---|---|
| C-O single bond | 5 | 5 | 1.0 |
| Hydroxyl (O-H) | 4 | 4 | 1.0 |
| Carbohydrate | 3 | 3 | 1.0 |
| Methoxy (OCH3) | 3 | 3 | 1.0 |
| Methacrylate | 3 | 3 | 1.0 |
| Acetate | 3 | 3 | 1.0 |
| C c single bond | 3 | 2 | 1.0 |
| Alkyl C-H | 3 | 2 | 1.0 |
| Metal oxygen | 2 | 2 | 1.0 |
| Chlorine | 2 | 1 | 1.0 |
| Alkene (C=C) | 2 | 1 | 1.0 |
| Nucleic acid | 1 | 1 | 1.0 |
| Silanol (Si-OH) | 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 |
| Aromatic ring | 1 | 1 | 1.0 |
| Bromine | 1 | 1 | 1.0 |
| Phosphorus | 1 | 1 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
| Aldehyde (CHO) | 1 | 1 | 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 |
|---|---|---|---|
| cellulose | 864, 1735, 1650 | C-O single bond, Hydroxyl (O-H), Methoxy (OCH3) | 1 |
| hydroxyapatite | 864, 1620, 1639 | 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 864 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
-
Acetate confidence 1.0
“Additional bands corresponding to C-O-H bending appeared at 1291 After treatment of wood samples with DES2, new peaks were formed at 1039, 952, 943 and cm-1, 864 which were C-O vibrations in hemicellulose and cellulose, a C-H deformation in”
Can 等 - 2023 - Choline Chloride-Based Deep Eutectic Solvent-Treat DOI: 10.3390/f14030569 -
Alkene (C=C) confidence 1.0
“cm-1 In the bands at 3009 in the reaction with IA (Figure 5b), the peak referring to cm-1 the double bond disappeared, promoting a stretching at 864 (Figure 6) and resulting”
Montenegro 等 - 2023 - Enzymatic and Synthetic Routes of Castor Oil Epoxi DOI: 10.3390/polym15112477 -
Aldehyde (CHO) confidence 1.0
“cm-1 formation at 864.11 is due to stretching vibration of -C-Na bond which also considered as the coupling reaction between -CHO from OSA and -NH 2”
Preparation of In Situ Cross - Linked N - Maleoyl Chitosan - Oxidized Sodium Alginate Hydrogels for Drug Delivery Applications DOI: 10.3889/oamjms.2019.850 -
Phosphate (PO4) confidence 1.0
“The small stretch at 864 cm-1 and 32corresponds to octacalcium phosphate and amorphous calcium 1378 cm-1”
Novel synthesis of bioactive hydroxyapatite/f-multiwalled carbon nanotube composite coating on 316L SS implant for substantial corrosion resistance and antibacterial activity DOI: 10.1016/j.jallcom.2018.10.341 -
Bromine confidence 1.0
“cm-1 The bands at 864 and 861 were assigned as C14HOOP in SRII (Figure 4c) and BR-T (d), respectively, the presence of which is highly correlated with negative pho- (28).”
Suzuki 等 - 2008 - Structural Changes of Salinibacter Sensory Rhodops DOI: 10.1021/bi801358b -
Carbohydrate confidence 1.0
“The presence of absorption peaks at about 3733, 3500, 3492, 2920, 2826, 1946, 1536, 1372, and 864 cm-1 were associated with the representative functional groups of cellulose [53,54].”
Characterizations of Alpha-Cellulose and Microcrystalline Cellulose Isolated from Cocoa Pod Husk as a Potential Pharmaceutical Excipient DOI: 10.3390/ma15175992 -
Acetate confidence 1.0
“cm-1 cm-1, All starches showed bands around 864 and 770 which were related to the stretching α-configuration vibration of C-O-C and C-O-H from glycosidic bonds.”
Antobelli Basilio-Cortes 等 - 2019 - Effect of Dual Modification on the Spectroscopic, DOI: 10.3390/polym11020333 -
Hydroxyl (O-H) confidence 1.0
“• Stretching vibrations of C-O bonds in COOH [21] Arenesovertonesduetomono-substitution(689cm-1 1905-1699 1905-1699 * • band)metadi-substitution(864cm-1 band) • O-H group in absorbed molecules of water and/or structural molecules of water o”
The Origin and Physico-Chemical Properties of Some Unusual Earth Rock Fragments DOI: 10.3390/app12030983
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