What absorbs at 3651 cm⁻¹ in an FTIR spectrum?
A band near 3651 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 7 cited sources
Quick answer
A band near 3651 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 |
|---|---|---|---|
| Hydroxyl (O-H) | 5 | 5 | 1,0 |
| Metal oxygen | 1 | 1 | 1,0 |
| Water (H2O) | 1 | 1 | 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 |
|---|---|---|---|
| kaolinite | 3651, 3696, 693 | Hydroxyl (O-H), Metal oxygen, Water (H2O) | 2 |
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 3651 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
-
Water (H2O) confiance 1,0
“analyzed by a deconvolution procedure, and the area of a cm-1) specific peak (at 3651 was directly correlated to the amount of water inside the sample.”
A spectroscopic approach to assess transport properties of water vapor in PLA DOI: 10.1016/j.polymertesting.2015.03.015 -
Hydroxyl (O-H) confiance 1,0
“γANPs-CTAB When we compare the FTIR spectra of before and after BPA adsorption (Figure 14a,b), it is observed that the intensities of the -OH stretching mode seen at 3651, cm-1 3643, and 3480 decrease after BPA adsorption.”
Low-Cost Synthesis of Alumina Nanoparticles and Their Usage for Bisphenol-A Removal from Aqueous Solutions DOI: 10.3390/pr9101709 -
Hydroxyl (O-H) confiance 1,0
“hydroxyl groups Al-O-H stretching of inner surface 3651 3651 3651 3651 3651 3651 3651 3651 3651 3651 hydroxyl groups Al-O-H stretching of inner hydroxyl 3619 3619 3619 3619 3619 3619 3619 3619 3619 3621”
Oyebanjo 等 - 2018 - Mineral Constituents and Kaolinite Crystallinity o DOI: 10.1515/geo-2018-0012 -
Hydroxyl (O-H) confiance 0,9
“Explicit assignment for kaolinite OH stretching.”
Weng 等 - 2020 - Black carbon enriches short-range-order ferrihydri DOI: 10.1016/j.scitotenv.2020.138195 -
confiance 0,9
“Explicit assignment in text”
Mineralogy and geochemistry of clay fractions in soils developed from different parent rocks in Limpopo Province, South Africa DOI: 10.1016/j.heliyon.2021.e07664 -
Hydroxyl (O-H) confiance 0,9
“Explicitly assigned to OH stretching region, compared to water monomer.”
Vibrational investigations of CO2-H2O, CO2-(H2O)2, and (CO2)2-H2O complexes isolated in solid neon DOI: 10.1063/1.4936913 -
Hydroxyl (O-H) confiance 0,8
“Assigned to stretching vibration of hydroxyl groups.”
Multi-Method Analysis of Painting Materials in Murals of the North Mosque (Linqing, China) DOI: 10.3390/coatings13071298
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