What absorbs at 618 cm⁻¹ in an FTIR spectrum?
A band near 618 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 618 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 |
|---|---|---|---|
| Metal oxygen | 6 | 6 | 1.0 |
| Alkyl C-H | 3 | 3 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 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 |
| Water (H2O) | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| Silicon silicon | 1 | 1 | 1.0 |
| Anhydride | 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 |
|---|---|---|---|
| polystyrene | 618, 1020, 1600 | Alkyl C-H, Amide, Hydroxyl (O-H) | 1 |
| iron oxide | 618, 1130, 891 | Alkyl C-H, Metal oxygen, Hydroxyl (O-H) | 1 |
| zinc oxide | 618, 1627, 1638 | Metal oxygen, Alkyl C-H, Amide | 1 |
| ZnO NPs | 618, 1664, 875 | Alkyl C-H, Hydroxyl (O-H), Metal oxygen | 1 |
| iron oxide nanoparticles | 618, 2972, 528 | Hydroxyl (O-H), Alkyl C-H, Metal oxygen | 1 |
| SnO2 | 618, 2800, 1547 | Metal oxygen, 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 618 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
-
confidence 1.0
“The peak at 848 corresponds to symmetric Ti-O stretching vibrations and 6 cm-1 the peak at 618 attribute to the asymmetric Ti-O stretching vibration.”
Fabrication of the flexible nanogenerator from BTO nanopowders on graphene coated PMMA substrates by sol-gel method DOI: 10.1016/j.matchemphys.2017.02.002 -
confidence 1.0
“The band at 618 is associated with Fe-O-H stretching”
Karpagavinayagam 和 Vedhi - 2019 - Green synthesis of iron oxide nanoparticles using DOI: 10.1016/j.vacuum.2018.11.043 -
Anhydride confidence 1.0
“The peaks at cm-1 cm-1 618 and 638 due to the stretching vibration of Co-O-Co (or Mn-O-Mn)”
Control of magnetic properties and band gap by Co/Mn ordering and oxygen distributions of La2CoMnO6 DOI: 10.1016/j.jmmm.2017.03.040 -
confidence 1.0
“CuNP vibration peaks were monitored at 1635 with FTIR and a cm-1 sharp peak at 617.6 is representing Cu-O group due to the occurrence of Cu 2O.”
Photovoltaic and Antimicrobial Potentials of Electrodeposited Copper Nanoparticle DOI: 10.1016/j.bej.2018.10.009 -
Silicon silicon confidence 1.0
“The signal around 618 cm-1 can be considered a Si-Si vibration [25] coming from cm-1 measurements.”
Surface Morphology and Optical Properties of Hafnium Oxide Thin Films Produced by Magnetron Sputtering DOI: 10.3390/ma16155331 -
Metal oxygen confidence 1.0
“The peak at 617.9 represented Zn-O stretching vibrations”
Successive Photocatalytic Degradation of Methylene Blue by ZnO, CuO and ZnO/CuO Synthesized from Coriandrum sativum Plant Extract via Green Synthesis Technique DOI: 10.3390/cryst13020281 -
Water (H2O) confidence 1.0
“Commons cm(cid:4)1 vibration.37 2 water molecules The sharp peak at 618”
Improved catalytic activity and bactericidal behavior of novel chitosan/V2O5 co-doped in tin-oxide quantum dots DOI: 10.1039/d2ra03975c -
confidence 1.0
“A strong absorption peak appears at 618 for BaTiO 3/PS, which corresponds to Ti-O stretching normal vibrations of the connected TiO octahedra.”
Fabrication of Europium-Doped Barium Titanate/Polystyrene Polymer Nanocomposites Using Ultrasonication-Assisted Method: Structural and Optical Properties DOI: 10.3390/polym14214664
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 literature-backed analysis — in seconds.