What absorbs at 525 cm⁻¹ in an FTIR spectrum?
A band near 525 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 525 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 | 5 | 5 | 1.0 |
| Silicon-oxygen (Si-O) | 5 | 5 | 1.0 |
| Silicon (Si) | 3 | 3 | 1.0 |
| Siloxane (Si-O-Si) | 2 | 2 | 1.0 |
| Carbonate | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Phosphate (PO4) | 1 | 0 | 1.0 |
| Phosphorus | 1 | 0 | 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 |
|---|---|---|---|
| montmorillonite | 525, 1637, 523 | Silicon-oxygen (Si-O), Silicon (Si) | 2 |
| CuO | 525, 453, 1000 | Metal oxygen | 1 |
| bentonite | 525, 882, 918 | Silicon-oxygen (Si-O), Silicon (Si), Siloxane (Si-O-Si) | 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 525 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
“BiO octahedral structure possesses 6 M cm-1 peaks at 525 and 450 due to the bending vibration of Bi-O.”
Francis 等 - 2016 - Optical nonlinearity in multiferroic bismuth ferri DOI: 10.1016/j.jallcom.2016.07.094 -
Metal oxygen confidence 1.0
“Wave number cm-1 The peak at 525 should be a stretching of Cu-O, which”
Padil 和 Cernik - 2013 - Green synthesis of copper oxide nanoparticles usin DOI: 10.2147/IJN.S40599 -
confidence 1.0
“One possible explanation for the appearance of the band at 525 cm-l could be due to the incorporation of Al atoms into the CON building units, leading to”
Park 等 - 2020 - Insight into the crystallization mechanism of the DOI: 10.1016/j.micromeso.2020.110213 -
Carboxyl (COOH) confidence 1.0
“All three samples show a desorption peak with maximum at around 525 K, as in the case of the AlPO sample, that would correspond to weak acid sites, and an additional desorption peak at higher temperature (with maximum at around 625 K), whic”
Alvaro-Munoz 等 - 2013 - Effect of silicon content on the catalytic behavio DOI: 10.1016/j.cattod.2013.04.031 -
Metal oxygen confidence 1.0
“cm-1 band indicates the presence of quartz, the 625 band stems from out-of-plane Al-O-Si cm-1 cm-1 vibrations, and the bands at 525 and 467 are related to Al oct-O-Si, and Si-O-Si bending vibrations, respectively.”
Rehydration Driven Na-Activation of Bentonite—Evolution of the Clay Structure and Composition DOI: 10.3390/ma14247622 -
confidence 1.0
“The main reduction peak at 490 K may be related to the direct reduction of extra-framework octahedral (Cu(II) whereas the reduction peak at 525 K may be related to the reduction of copper oxides occurring in zeolite pores in line with earli”
High activity of mononuclear copper present in the framework of CuSiBEA zeolites in the selective catalytic reduction of NO with NH3 DOI: 10.1016/j.micromeso.2015.11.065 -
confidence 1.0
“cm-1 A strong complex band at 1037 is attributed to the stretching vibration of the Si-O groups cm-1 cm-1 of the tetrahedral sheets and the absorption bands at 525 and 467 belong to Si-O-Al cm-1,”
Du 等 - 2020 - Synthesis, Property and Mechanism Analysis of a No DOI: 10.3390/min10020128 -
confidence 1.0
“The weak for the loss of the physically adsorbed water and the second 525cm-1 153.9∘ band at is bending vibration of Si-O-Al and the C corresponding to the endothermic valley appears at 834cm-1”
Li 等 - 2014 - Preparation and Characterization of Montmorillonit DOI: 10.1155/2014/167402
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