What absorbs at 715 cm⁻¹ in an FTIR spectrum?
A band near 715 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 715 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 |
|---|---|---|---|
| Alkyl C-H | 4 | 4 | 1.0 |
| Metal oxygen | 4 | 4 | 1.0 |
| Carbonate | 3 | 3 | 1.0 |
| Sulfur | 1 | 1 | 1.0 |
| Methacrylate | 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 |
| Acetate | 1 | 1 | 1.0 |
| C-S single bond | 1 | 1 | 1.0 |
| S eq o | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Hydrogen bond | 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 |
|---|---|---|---|
| TiO2 | 715, 1700, 1093 | Metal oxygen, Alkyl C-H | 1 |
| Al2O3 | 715, 1722, 1383 | Metal oxygen, Alkyl C-H | 1 |
| TiO2 nanoparticles | 715, 1700, 455 | Alkyl C-H, Metal oxygen | 1 |
| curcumin | 715, 1063, 1153 | 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 715 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
-
Carbonate confidence 1.0
“LLM confirmed rule peak-group candidate”
Awonusi 等 - 2007 - Carbonate assignment and calibration in the raman DOI: 10.1007/s00223-007-9034-0 -
Hydrogen bond confidence 1.0
“In addition, a 720 cm-1 peak, which is one of the PCM char- (2) the hydrogen bonding between the paraffin and the lignin, cellulose, and hemicellulose acteristic peaks, appeared at 715 cm-1 in wood samples.”
n-Heptadecane-Impregnated Wood as a Potential Material for Energy-Saving Buildings DOI: 10.3390/f13122137 -
Metal oxygen confidence 1.0
“A strong band observed at around ~715 is assigned to phonon band of the metal oxide lattice.”
Oxygen vacancies and F+ centre tailored room temperature ferromagnetic properties of CeO2 nanoparticles with Pr doping concentrations and annealing in hydrogen environment DOI: 10.1016/j.jallcom.2020.156079 -
Alkyl C-H confidence 1.0
“From this figure, it is (cid:3)CforVG30, seen that,thetransitionisobservedat25 The C-H rocking vibration in the region between 715 (cid:3)C (cid:3)C at 35 for PMB-P and PMB-E and at 45 for and735cm(cid:4)1 hasbeenpreferredtoidentifychangesi”
Transitions in unmodified and modified bitumen using FTIR spectroscopy DOI: 10.1617/s11527-018-1308-7 -
Alkyl C-H confidence 1.0
“Spectrum of the PE film before irradiation show the 05 characteristic absorption peaks of long alkyl chain in the 2919cm-1, 2857cm-1, 1475cm-1, 715cm-1.”
Asghar 等 - 2011 - Comparative Solid Phase Photocatalytic Degradation DOI: 10.1155/2011/461930 -
Alkyl C-H confidence 1.0
“The peak obtained at 715 with a medium intensity was due to the in-plane asymmetric deformation of CH 2.”
The Influence of Emulsifiers on the Physiochemical Behavior of Soy Wax/Rice Bran Oil-Based Oleogels and Their Application in Nutraceutical Delivery DOI: 10.3390/gels9010047 -
Metal oxygen confidence 1.0
“400-700cm-1 extending band in the range indicates the can be assigned to the Al-O stretching mode in octahedral structure;bandsaround715cm-1 and1072cm-1 existence of amorphous structure or disordered defects).”
Djebaili 等 - 2015 - XPS, FTIR, EDX, and XRD Analysis of Al2O3 Scales G DOI: 10.1155/2015/868109 -
Metal oxygen confidence 1.0
“LLM confirmed rule peak-group candidate”
A Highly Selective Novel Green Cation Exchange Membrane Doped with Ceramic Nanotubes Material for Direct Methanol Fuel Cells DOI: 10.3390/en14185664
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