What absorbs at 3639 cm⁻¹ in an FTIR spectrum?
A band near 3639 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 3 cited sources
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 0 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Literature behind these assignments
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confidence 1.0
“cm-1 cm-1 cm-1 brations at 3639 cm-1 for -OH, 2860 cm-1 for -C-H, 2487 cm-1 for -C≡C-, 1625 cm-1 for -N-H, -C≡C-, vibrations at 3639 for -OH, 2860 for -C-H, 2487 for 1625 for cm-1 cm-1 cm-1 for -COOH, 1053 cm-1 for -C-F, and 530 cm-1 for Ca”
Biosynthesis and Characterization of Calcium Oxide Nanoparticles from Citrullus colocynthis Fruit Extracts; Their Biocompatibility and Bioactivities DOI: 10.3390/ma16072768 -
Hydroxyl (O-H) confidence 1.0
“The hydroxyl stretch regions for octahedra and rods look cm(cid:2)1 quite similar, showing a strong band at 3639 for bridging cm(cid:2)1 hydroxyls, with a shoulder at 3669 arising from single-co-”
Exposed Surfaces on ShapeControlled Ceria Nanoparticles Revealed through ACTEM and WaterGas Shift Reactivity DOI: 10.1002/cssc.201300651 -
Hydroxyl (O-H) confidence 1.0
“The absorption peak cm-1 at 3639.02 has also resulted due to the O-H bond from water molecules on the surface of the cm-1 nanoparticle [18,24].”
Habte 等 - 2019 - Synthesis of Nano-Calcium Oxide from Waste Eggshel DOI: 10.3390/su11113196
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