What absorbs at 868 cm⁻¹ in an FTIR spectrum?
A band near 868 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 868 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 |
|---|---|---|---|
| Carbonate | 2 | 2 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Nitrogen heterocycle | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Possible materials
| Material | Supporting peaks | Overlapping groups | Cited sources |
|---|---|---|---|
| activated carbon | 868, 1575, 1210 | Alkyl C-H, Aromatic ring | 1 |
| CS | 868, 1645, 1720 | 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 868 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
“cm-1) cm-1), cm-1).9, 10 CH stretching (954 and C-C vibration (868 -CHbending (754 and 1383 cm-1 The peak at 872 observed in all samples which is due to C-C stretching and featured for cm-1 amorphous properties of films.”
Ghosh 等 - 2020 - Blown films fabrication of poly lactic acid based DOI: 10.1016/j.mtcomm.2019.100737 -
confidence 1.0
“In the FTIR analysis, a dominant peak at 868 wavenumbers Keywords: corresponding to the longitudinal optical (LO) mode of monoclinic TiO2phase was observed at 10% oxygen TiO2”
Structural and optical properties investigation of DC magnetron sputtered β-TiO2 thin film DOI: 10.1016/j.apsusc.2014.08.131 -
Carbonate confidence 1.0
“FTIR spectra establishes a particular Calcite - Zincite nano powder obtained the characteristic peak of carbonate group at 1414 cm-1, 868 cm-1 (CaCo3) and 477 cm-1 (ZnO).”
Kumar 等 - 2020 - Synthesis of calcite-zincite nano composite materi DOI: 10.1088/1757-899X/1003/1/012132 -
Nitrogen heterocycle confidence 1.0
“Moreover, a catalytic and the peaks at 1355 and 1523 correspond structure.16 effect was observed when alumina fillers were added, as shown to triazine ring in poly(triazine) The peaks at 868”
Tay 等 - 2022 - Simultaneous Enhancement of Polymerization Kinetic DOI: 10.1021/acsomega.2c02667 -
Acetate confidence 1.0
“The bands at about 1436 and 1728 are C=O to P-O bending (crystalline) and P-O bending (amorphous), associated with C-O (Stretch) and (Stretch) stretching cm-1 cm-1 band respectively, presence of C-O stretching at 868 modes, respectively, an”
Vyas 等 - 2016 - Effect of nickel oxide substitution on bioactivity DOI: 10.1007/s12034-016-1242-7 -
confidence 1.0
“The new characteristic peaks at 3732 3672 32CO istic peaks of group in pure bastnaesite spectrum are 729 cm-1, 868 cm-1, 1087 cm-1 cm-1 and 3648 of bastnaesite treated with NHA are caused by the tensile vibration of N-H”
Selective Adsorption of 2-Hydroxy-3-Naphthalene Hydroxamic Acid on the Surface of Bastnaesite and Calcite DOI: 10.3390/min12111341 -
Aromatic ring confidence 1.0
“The peak of 868 cm-1 is assigned to the aromatic nucleus (C-H), and one adjacent H deformation.”
Zhao 等 - 2022 - Differences in Macromolecular Structure Evolution DOI: 10.3390/en15155334 -
confidence 0.9
“Explicit assignment in text.”
Fabrication and Characterization of Activated Carbon from Phyllostachys edulis Using Single-Step KOH Activation with Different Temperatures DOI: 10.3390/pr10091712
Have a spectrum with this band?
Upload your FTIR spectrum and get a full interpretation report — peak assignments with literature citations, library matches, and a confidence-rated evidence chain — in seconds.