What absorbs at 915 cm⁻¹ in an FTIR spectrum?
A band near 915 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 915 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 |
|---|---|---|---|
| Oxygen heterocycle | 8 | 7 | 1.0 |
| Hydroxyl (O-H) | 5 | 4 | 1.0 |
| Silicon (Si) | 3 | 3 | 1.0 |
| Silicon-oxygen (Si-O) | 3 | 2 | 1.0 |
| Alkyl C-H | 3 | 2 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Siloxane (Si-O-Si) | 1 | 1 | 0.9 |
| N-O bond | 1 | 0 | 1.0 |
| Carboxyl (COOH) | 1 | 0 | 0.9 |
| Metal hydroxyl | 1 | 0 | 0.9 |
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 |
|---|---|---|---|
| epoxy resin | 915, 905, 1100 | Oxygen heterocycle | 1 |
| clay | 915, 1736, 2855 | Silicon-oxygen (Si-O), Hydroxyl (O-H), Silicon (Si) | 1 |
| epoxy | 915, 1660, 1735 | Oxygen heterocycle | 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 915 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
-
Alkyl C-H confidence 1.0
“In both cases the characteristic absorption bands are showed: 1509 and 1608 cm-1 (C=C bonds of aromatic ring), 1457 cm-1 (CH2 group vibration), 1362 cm-1 (methyl group vibration) and 915 cm1 (epoxy ring).”
Barbadillo 等 - 2003 - Study of a curing reaction of an epoxy resin DOI: 10.4028/www.scientific.net/MSF.426-432.2163 -
Hydroxyl (O-H) confidence 1.0
“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 cm-1, conjugated to them the bending vibrations at 915, 916, and 9”
Enhanced Coating Protection of C-Steel Using Polystyrene Clay Nanocomposite Impregnated with Inhibitors DOI: 10.3390/polym15020372 -
Amide confidence 1.0
“In cm-1 cm-1, 5-10cm-1 by 40 downshifts the broad band from 1,653 redshift in their particular, two bands exhibit a ν(CH 13C-labelling agreeing well with the expected behavior of the amide I mode 2) stretching frequencies upon of methylene”
Baserga 等 - 2022 - Membrane Protein Activity Induces Specific Molecul DOI: 10.3389/fmolb.2022.915328 -
Oxygen heterocycle confidence 1.0
“spectrum of epoxy-paint indeed shows the disappearance of the The irradiated samples are characterized by absorption bands cm(cid:2)1 band at 915 characteristic of the deformation of the epoxy cm(cid:2)1.”
A FTIR/chemometrics approach to characterize the gamma radiation effects on iodine/epoxy-paint interactions in Nuclear Power Plants DOI: 10.1016/j.aca.2017.01.005 -
Hydroxyl (O-H) confidence 1.0
“The presence of cm-1, 915 attributed to OH deformations of kaolinite, is visible up to temperatures of 500 the doublets at 915 cm-1, attributed to OH deformations of kaolinite, is visible up to tem-”
The Interdisciplinary Approach of Some Middle Bronze Age Pottery from Eastern Romania DOI: 10.3390/app11114885 -
Alkyl C-H confidence 1.0
“The vibration at a 915cm(cid:5)1canalsobeattributedtotheSi(cid:5)CH nbonds.[37,38]A s>3008C values observed for films deposited at T are Si(cid:5)(CH n(cid:5)Si comparabletotheR significant decrease in the intensity of aobservedforSiN xfilm”
Atmospheric Pressure Plasma CVD of Amorphous Hydrogenated Silicon Carbonitride (aSiCN:H) Films Using Triethylsilane and Nitrogen DOI: 10.1002/ppap.201100035 -
Hydroxyl (O-H) confidence 1.0
“The shoulder 1111, 1095, 1037, 1020, and 1000 cm-1 Al/Mg20-30 μm corresponds to bending of <20, for bare fallow, native steppe, and cropland: with a maximum at 915 cm-1 O-H vibrations.57 The 860 band corresponds to bending these bands have”
Krivoshein 等 - 2022 - FTIR Photoacoustic and ATR Spectroscopies of Soils DOI: 10.1021/acsomega.1c05702 -
confidence 1.0
“FA-1 shows a shoulder peak at about 915 cm-1 associated with the presence of aluminum in the octahedral of FA-2 are sharper than the bands for FA-1, which is attributed to the increased order of the silicate position, confirming the existen”
Structural Characterizations of Aluminosilicates in Two Types of Fly Ash Samples from Shanxi Province, North China DOI: 10.3390/min9060358
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