What absorbs at 3625 cm⁻¹ in an FTIR spectrum?
A band near 3625 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 3625 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.
Возможные назначения функциональных групп
| Функциональная группа | Подтверждающие факты | Цитируемые источники | Максимальная достоверность |
|---|---|---|---|
| Hydroxyl (O-H) | 5 | 5 | 1,0 |
| Methyl | 1 | 1 | 1,0 |
| Methoxy (OCH3) | 1 | 1 | 1,0 |
| Methacrylate | 1 | 1 | 1,0 |
| Alkyl C-H | 1 | 1 | 1,0 |
| Acetate | 1 | 1 | 1,0 |
| Water (H2O) | 1 | 1 | 1,0 |
| Silanol (Si-OH) | 1 | 1 | 1,0 |
| Silicon (Si) | 1 | 1 | 1,0 |
| Metal oxygen | 1 | 1 | 1,0 |
| Silicate | 1 | 1 | 0,9 |
| Silicon-oxygen (Si-O) | 1 | 1 | 0,8 |
Ранжирование отражает накопленные литературные данные, а не единственное авторитетное правило. Всегда проверяйте в контексте вашего образца.
Possible materials
| Материал | Поддерживающие пики | Overlapping groups | Цитируемые источники |
|---|---|---|---|
| clay | 3625, 1736, 2855 | Hydroxyl (O-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 3625 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.
Литература, лежащая в основе этих назначений
-
Hydroxyl (O-H) достоверность 1,0
“Interpretation and discussion 3625cm-1 O-H-stretching frequencies near the band.”
The nature of interlayering in clays from a podzol (Spodosol) from the Tatra Mountains, Poland DOI: 10.1016/j.geoderma.2010.10.013 -
Hydroxyl (O-H) достоверность 1,0
“As shown in the clay spectra of RC, cm-1, NaC and OC, there are absorption bands at the frequencies 3626, 3629, and 3625 which refer to the stretching vibrations of the (O-H) bonds in Al-OHs, respectively, and”
Enhanced Coating Protection of C-Steel Using Polystyrene Clay Nanocomposite Impregnated with Inhibitors DOI: 10.3390/polym15020372 -
достоверность 1,0
“cm-1 Moreover, the appearance of a new band at 3625 was due to formation of Mn-O(H)-Si moieties (Scheme 1, Structure C), similar to acidic hydroxyl groups typical for zeolite materials.”
Incorporation of Mn into the vacant T-atom sites of a BEA zeolite as isolated, mononuclear Mn: FTIR, XPS, EPR and DR UV-Vis studies DOI: 10.1039/c6cp01713d -
Hydroxyl (O-H) достоверность 1,0
“The band at cm-1 Methylene blue (Sigma-Aldrich) was used in the adsorption study 3625 was assigned to the stretching vibration of structural OH 448cm-1were purification.”
Sodium montmorillonite/ureasil-poly(oxyethylene) nanocomposite as potential adsorbent of cationic dye DOI: 10.1016/j.clay.2017.11.009 -
Silanol (Si-OH) достоверность 1,0
“diatomite presented distinctive bands at 3625, 1633, 1433, 1043, 795 and 448 The cm-1 was due to the free silanol group (SiO-H) (Khraisheh et al., 2005;”
El Ouardi 等 - 2020 - An insight of enhanced natural material (calcined DOI: 10.1016/S0043-1354(01)00071-9 -
достоверность 1,0
“Fine particles of RHA, slag, and spherical particles Cem3,4,and5mortars.Thebandat3822cm-1 or3625cm-1 ofFAfillthesmallporesofZ-Cemandconsequentlyincrease may be due to the presence of calcium hydroxide.”
Karim 等 - 2015 - Development of a Zero-Cement Binder Using Slag, Fl DOI: 10.1155/2015/247065 -
Water (H2O) достоверность 1,0
“2355.9702 Atmospheric CO 2 3432.0896 Adsorbed water vibrations (H-O-H) 3624.6269 Inner OH groups, lying between the sheets of tetrahedral and octahedral units”
Structural Study of Nano-Clay and Its Effectiveness in Radiation Protection against X-rays DOI: 10.3390/nano12142332 -
Hydroxyl (O-H) достоверность 1,0
“the characteristic peak near 1535 in the spectrum 3 FTIR spectra of NHA, 3752 cm-1 and 3625 cm-1 are the stretching vibrations of -OH with”
Selective Adsorption of 2-Hydroxy-3-Naphthalene Hydroxamic Acid on the Surface of Bastnaesite and Calcite DOI: 10.3390/min12111341
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