What absorbs at 688 cm⁻¹ in an FTIR spectrum?
A band near 688 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 688 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.
Attributions possibles de groupes fonctionnels
| Groupe fonctionnel | Faits à l＇appui | Sources citées | Confiance maximale |
|---|---|---|---|
| Metal oxygen | 3 | 2 | 1,0 |
| Aromatic ring | 2 | 2 | 1,0 |
| Borate | 1 | 1 | 1,0 |
| Ring structure | 1 | 1 | 1,0 |
| Amide | 1 | 1 | 1,0 |
| Silicon (Si) | 1 | 1 | 1,0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1,0 |
| Hydroxyl (O-H) | 1 | 0 | 1,0 |
| Metal hydroxyl | 1 | 0 | 1,0 |
Le classement reflète les preuves bibliographiques accumulées, et non une règle faisant autorité. Confirmez toujours dans le contexte de votre échantillon.
Possible materials
| Matériel | Pics de support | Overlapping groups | Sources citées |
|---|---|---|---|
| ZnO | 688, 1400, 3430 | Metal oxygen | 1 |
| kaolinite | 688, 3696, 693 | Metal oxygen | 1 |
| nanocomposites | 688, 1717, 1630 | Ring structure | 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 688 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.
Bibliographie derrière ces attributions
-
confiance 1,0
“The peak cm-1 at 602 can be attributed to terminal oxygen vibration cm-1 of Sn-OH, while the peak appearing at 688 is due to (F1).”
Synthesis, structural and optical properties of Fe-doped nanocrystalline SnO2 DOI: 10.1007/s10854-017-7018-z -
confiance 1,0
“In addition to the Ni-O Characterization above bands, the characteristic absorption band of obcm-1 served at 688 corresponds to the stretching vibrations of Ni-O.ItwasobservedthatwiththeadditionofNiOinPMOTFourier transform infrared (FTIR) s”
Sehgal 和 Narula - 2015 - Structural, morphological, optical, and electrical DOI: 10.1007/s00396-015-3663-z -
confiance 1,0
“reveals the characteristic vibrational bands at 557, 688, 717, 881, 935 and 1039 The cm-1 vibrational modes at 557 and 717 are assigned to the structural vibrations of yttrium-oxygen cm-1 (Y-O) bonds, the peak at 688 to the stretching mode”
Luminescence and electron spin resonance studies of narrow-band UVB emitting Gd3+ doped Y2SiO5 nanophosphors synthesized by sol-gel method DOI: 10.1016/j.ijleo.2021.167228 -
Silicon (Si) confiance 1,0
“cm-1 Three medium bands appeared at 688, 752 and 795 were assigned to the deformation modes of AlVI-O-Si bands [21-22].”
Souissi 等 - 2022 - Synthesis, Thermal Properties and Electrical Condu DOI: 10.21203/rs.3.rs-1294285/v1 -
Amide confiance 1,0
“582cm-1 The peaks at 688 and 900 and have been previously assigned to the α-form of various b nylons16-20 as the amide V and VI, respectively.”
[gamma]-Crystalline form of nylon-10,10 in nylon-10,10-montmorillonite nanocomposite DOI: 10.1002/pi.1154 -
Aromatic ring confiance 1,0
“Meanwhile, C=C of aromatic ring vibrations were observed at 687.5 the presence of these peak intensities is attributed to pure cinnamaldehyde (Figure 6 (b;”
Alamier 等 - 2022 - Thermodynamic and Spectroscopic Studies of SDS in DOI: 10.3390/app122312020 -
Borate confiance 1,0
“The absorption peaks at 687.62, 953.71 and 1345.78 attribute to borate network according to Table 3.”
Facile Synthesis of Calcium Borate Nanoparticles and the Annealing Effect on Their Structure and Size DOI: 10.3390/ijms131114434 -
Metal oxygen confiance 1,0
“1554 - 1427 Zn-O stretching 688 450”
Fadillah 等 - 2017 - Fabrication and Characterization of ZnO and Li dop DOI: 10.1063/1.4991157
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