What absorbs at 709 cm⁻¹ in an FTIR spectrum?
A band near 709 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 6 cited sources
Quick answer
A band near 709 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 |
|---|---|---|---|
| Silicon nitrogen | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| Adsorbed carbon monoxide | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Chlorine | 1 | 1 | 1.0 |
| Metal oxygen | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 0.8 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
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 709 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
-
Metal oxygen confidence 1.0
“The absorption bands in the 709(cid:2)100cm(cid:2)1 region were attributed to the envelope Ce(cid:2)O Y(cid:2)O of the phonon band of the metal oxide or 468cm(cid:2)1 vibrations.”
Jeyanthi 等 - 2013 - STRUCTURAL ANALYSIS OF THE COMBUSTION SYNTHESIZED DOI: 10.1142/S0218625X13500376 -
confidence 1.0
“709 The presence of these bands indicated the existence of C-Cl stretching, which can be attributed to the presence of calcium chloride in the sealer material itself.”
Assiry 等 - 2023 - Microstructural and Elemental Characterization of DOI: 10.3390/app13074517 -
Water (H2O) confidence 1.0
“cm-1 The absorption bands at 1639 enlightened the existence starch.2,19 C�C of stretching in alkali-isolated The peaks at cm-1 709 indicated low content of coordinated water molecules due to wagging (out-of-plane bending) vibrations”
Malik 等 - 2022 - Improvement in Digestion Resistibility of Mandua S DOI: 10.1021/acsomega.2c02327 -
Adsorbed carbon monoxide confidence 1.0
“their carbon monoxide photolysis band at 709 A.”
Comparison of redox and ligand binding behaviour of yeast and bovine cytochrome c oxidases using FTIR spectroscopy DOI: 10.1016/j.bbabio.2018.05.018 -
Silicon (Si) confidence 1.0
“The band at cm-1, higher energy, 709 is assigned to Si-N stretching vibration [18, 19].”
Structure and ionic conductivity of nitrated lithium disilicate (LiSiON) glasses DOI: 10.1016/j.matchemphys.2018.02.045 -
Carbonyl (C=O) confidence 0.8
“Explicit assignment: '709cm-1 stretching is shown for crystalline PTX'”
Zhao 等 - 2015 - Preparation and Characterization of Paclitaxel Loa DOI: 10.1155/2015/913254
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