What absorbs at 935 cm⁻¹ in an FTIR spectrum?
A band near 935 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 935 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 |
|---|---|---|---|
| Alkyl C-H | 4 | 4 | 1.0 |
| C-O single bond | 3 | 3 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Silanol (Si-OH) | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
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 |
|---|---|---|---|
| wood | 935, 1740, 1730 | Alkyl C-H, C-O single bond | 1 |
| sodium alginate | 935, 1636, 1080 | Alkyl C-H, C-O single bond, Carboxyl (COOH) | 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 935 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
-
Carboxyl (COOH) confidence 1.0
“analysis of defined PLA/lactide mixtures, and then tested by isolated peak at a wavenumber of 935 This band is various means for their accuracy with respect to conversion mode.16 assigned to the COO ring breathing The signal used”
Braun 等 - 2006 - Infrared spectroscopic determination of lactide co DOI: 10.1021/ma061922a -
confidence 1.0
“It is possible that the new peak of 933.03 eV may be due to Cu (I) species, while the energy band of 935.23 eV could be assumed to be due to Cu”
Ibrahim 等 - 2022 - Effect of Ammonium Sulfide on Sulfidization Flotat DOI: 10.3390/min12101193 -
Silanol (Si-OH) confidence 1.0
“cm-1 vibrational modes at 557 and 717 are assigned to the structural vibrations of yttrium-oxygen cm-1 (Y-O) bonds, the peak at 688 to the stretching mode of Si-O (ν 3) units, the band position at of cm-1 cm-1 881 to the structural units of”
Luminescence and electron spin resonance studies of narrow-band UVB emitting Gd3+ doped Y2SiO5 nanophosphors synthesized by sol-gel method DOI: 10.1016/j.ijleo.2021.167228 -
confidence 1.0
“A strong peak at 935 is cm-1 ACN medium remained rather unchanged at 1643 i.e., attributed to the axial oxygen atoms of the uranyl ion in the”
Verma 等 - 2018 - Structural investigations on uranium(VI) and thori DOI: 10.1039/C7NJ04460G. -
C-O single bond confidence 1.0
“The band at 935 cm-1 can be attributed to the inulin glycosidic bond difficult”
Influence of Oxidation Degree on the Physicochemical Properties of Oxidized Inulin DOI: 10.3390/polym12051025 -
C-O single bond confidence 1.0
“The peaks at less than 950 are due to diagnostic cm-1 carbohydrate skeletal modes (Synytsya & Novak, 2014), the band at 935 being β2→1 characteristic of inulin and attributed to the glycosidic bond (Bekers, Grube, Upite, cm-1, Kaminska, Dan”
Physical characterization and in silico modeling of inulin polymer conformation during vaccine adjuvant particle formation DOI: 10.1016/j.carbpol.2016.01.062. -
Acetate confidence 1.0
“The characteristic peaks at 2951 cm-1 present the C-H stretching of the alkane groups, while the peak band at 935 cm-1 represents the C-O stretching vibration.”
Bhatia 等 - 2023 - The Effect of Sage (Salvia sclarea) Essential Oil DOI: 10.3390/gels9030233 -
Alkyl C-H confidence 1.0
“Las bandas más cm-1), cm-1), características fueron las de grupos OH (3 335 enlaces C-H (2 935 cm-1), C=O en carbohidratos y lignina (1 705 C=C de anillo conjugado en alcohol cm-1), cm-1), aromático (1 645 tensión de anillo arilo de lignina”
Contreras Quiñones 等 - 2022 - DOI: 10.29298/rmcf.v13i72.1186
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