What absorbs at 3660 cm⁻¹ in an FTIR spectrum?
A band near 3660 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 4 cited sources
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Hydroxyl (O-H) | 3 | 2 | 1.0 |
| Sulfate (SO4) | 1 | 1 | 1.0 |
| Silicon hydride | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Literature behind these assignments
-
Silicon hydride confidence 1.0
“cm-1) cm-1) 3660 and Si-H peak (observed at 2160 417 (1997) relative to Si-O-Si peak as a function of film thickness.”
Bougharouat 等 - 2011 - Plasma polymerization of TEOS for QCM-based VOC va DOI: 10.1051/epjap/2011110144 -
Hydroxyl (O-H) confidence 1.0
“O-H) 3440-cm-1 (bonded might be responsible for the O-H) 3660-cm-1 (unbonded bands and a 1:2 and the adductofwater-etheroxygensisresponsibleforthe3500H-O-H cm-1 3660-cm-1 (symmetric stretching) and the H-O-H (asymmetric stretching) bands.”
Maeda - 2001 - IR spectroscopic study on the hydration and the ph DOI: 10.1021/la001346q -
Hydroxyl (O-H) confidence 1.0
“bands also move closer together, with the separation decreasing and two far less intense bands at 3660 and 3484cm(cid:3)1 97cm(cid:3)1 94cm(cid:3)1 from that can be attributed to the surface hydroxyl groups for well crystallized goethite to”
Spectroscopic characterization of iron ores formed in different geological environments using FTIR, XPS, Mössbauer spectroscopy and thermoanalyses DOI: 10.1016/j.saa.2014.10.090 -
Sulfate (SO4) confidence 1.0
“Difference spectra 2of aqueous (a) (NH 4) cm-1 the only small weak negative peak around 3660 was SO 4, (b) Na 2SO 4, (c) MgSO 4, and (d) ZnSO solutions subtracted by 4 tentatively related to the effect of sulfate ions in the present pure wa”
Wei 等 - 2005 - Observation of the first hydration layer of isolat DOI: 10.1021/jp0453865
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