What absorbs at 706 cm⁻¹ in an FTIR spectrum?
A band near 706 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 706 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 | 3 | 3 | 1.0 |
| Amide | 2 | 2 | 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 |
| Acetate | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
| Borate | 1 | 1 | 1.0 |
| Carbonate | 1 | 1 | 0.9 |
| Boron nitrogen | 1 | 0 | 0.9 |
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 |
|---|---|---|---|
| AuNPs | 706, 1646, 1721 | Amide, Methacrylate | 1 |
| nanocomposite | 706, 2921, 3300 | Methacrylate, Metal oxygen | 1 |
| cellulose | 706, 1735, 1650 | Methacrylate, Amide | 1 |
| biochar | 706, 1640, 1115 | Methacrylate | 1 |
| wood | 706, 1740, 1730 | Methacrylate | 1 |
| calcite | 706, 2850, 2864 | Methacrylate, Amide | 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 706 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 FT-IR cm-1 spectrum showed a broad peak at 706 due to Ti-O”
Anjum 等 - 2023 - Photocatalytic degradation of reactive violet 1 by DOI: 10.30955/gnj.004281 -
Borate confidence 1.0
“The absorption band [8], 706cm-1 is assigned to B-O-B bending vibration, the at (cid:5) Bexp(cid:4) cm-1 is due to the stretching band between 1100 and 800 hν , α (ν) = 4]- [BO (3) tetrahedral borons and broad absorption modes of (cid:2)E c”
Kolavekar 等 - 2017 - Characterization and optical properties of Pr2O3-d DOI: 10.1007/s12034-017-1400-6 -
Amide confidence 1.0
“FTIR spectra of CNF/AuNPs/anti-colistin Ab, and exhibited Validation study cm-1, cm-1, cm-1 transmittance peaks at 706 1246 and 1514 corresponding to amide IV, due to presence of OCN banding;”
Kumar 等 - 2022 - Electrochemical immunosensor for the detection of DOI: 10.1007/s13205-022-03252-w -
Alkyl C-H confidence 1.0
“The peak at 706 is assigned to alkyl bendbiochars from unmixed substrates at 650 °C are more stabi-”
Biochar from co-pyrolysis of urban organic wastes—investigation of carbon sink potential using ATR-FTIR and TGA DOI: 10.1007/s13399-020-01000-9 -
Silicon (Si) confidence 1.0
“cm-1 symmetric stretching vibrations of inner Si/Al-O structure, respectively), 1180 and ZY characteristic peaks were found at 1050 cm-1 and 706 cm-1 (asymmetric and sym4 cm-1 788 (asymmetric and symmetric stretching vibrations of external”
Novel Biocomposite Films Based on High Methoxyl Pectin Reinforced with Zeolite Y for Food Packaging Applications DOI: 10.3390/foods11030360 -
Acetate confidence 1.0
“The band at 1,706 cm-1 is ascribed to the stretching vibration C=O, wavenumber of 3460 [47,48].”
Xu 等 - 2019 - New Perspective on Wood Thermal Modification Rele DOI: 10.3390/polym11071145 -
Metal oxygen confidence 0.9
“attributed to Ag-O stretching vibration”
Al-Qahtani 等 - 2022 - Structural, morphological, optical and electrochem DOI: 10.15251/JOR.2022.182.187 -
Carbonate confidence 0.9
“V4 mode of calcite”
Loy 等 - 2016 - Effects of Calcination on the Crystallography and DOI: 10.1155/2016/2914368
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