What absorbs at 943 cm⁻¹ in an FTIR spectrum?
A band near 943 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 943 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 |
|---|---|---|---|
| Methoxy (OCH3) | 4 | 4 | 1.0 |
| Methacrylate | 4 | 4 | 1.0 |
| C-O single bond | 4 | 4 | 1.0 |
| Acetate | 4 | 4 | 1.0 |
| Alkyl C-H | 4 | 4 | 1.0 |
| Metal oxygen | 3 | 3 | 1.0 |
| Hydroxyl (O-H) | 3 | 3 | 1.0 |
| Silanol (Si-OH) | 3 | 3 | 1.0 |
| Silicon-oxygen (Si-O) | 3 | 3 | 1.0 |
| Phosphate (PO4) | 3 | 3 | 1.0 |
| N-O bond | 2 | 2 | 1.0 |
| Oxygen heterocycle | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Phosphorus | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Siloxane (Si-O-Si) | 1 | 1 | 0.7 |
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 |
|---|---|---|---|
| PDMS | 943, 873, 1080 | Methoxy (OCH3), Methacrylate | 1 |
| TiO2 | 943, 1700, 1093 | Methacrylate, Acetate, C-O single bond | 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 943 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
-
Acetate confidence 1.0
“After treatment of wood samples with DES2, new peaks were formed at 1039 cm-1, 952 cm-1, 943 cm-1, and 864 cm-1, which were C-O vibrations in hemicellulose and cellulose, a C-H deformation in cellulose, and out-of-plane C-H out-of-plane aro”
Can 等 - 2023 - Choline Chloride-Based Deep Eutectic Solvent-Treat DOI: 10.3390/f14030569 -
N-O bond confidence 1.0
“The UV irradiation in the presence of gave cm-1 cm-1, 1250-1120 with Figure 5B and C shows that the 943 (X) band in no absorption bands at 943 and assigned to cm-1 H 2O shifts only slightly to 926 or 931 in D 2O.”
Nakamura 等 - 2003 - In situ FTIR studies of primary intermediates of p DOI: 10.1021/ja029503q -
Phosphate (PO4) confidence 1.0
“9 (2010) 943 cm-1 A prominent and strong peak due to P=O stretching vibrations of the PO4 was observed at 986.3 along cm-1”
Growth and characterization of calcium hydrogen phosphate dihydrate crystals from single diffusion gel technique DOI: 10.1002/crat.200900700 -
Metal oxygen confidence 1.0
“Suspensions were prepared using under aqueous alkaline photocatalysis study anatase TiO 2 deionized water (Millipore, Milli-Q, resistivity 18 MΩ cm) and conditions and attributed an asymmetric band peaking at 943 were sonicated for a durati”
Savory 等 - 2011 - Shallow Electron Trap, Interfacial Water, and Oute DOI: 10.1021/jp102723u -
Silicon (Si) confidence 1.0
“Besides, the absorption band at about cm-1 943 can be associated with stretching mode of Si-OH cm-1 [39].”
Magnetron sputtering technique for analyzing the influence of RF sputtering power on microstructural surface morphology of aluminum thin films deposited on SiO2/Si substrates DOI: 10.1007/s00339-021-04892-0 -
Phosphate (PO4) confidence 1.0
“Particularly significant is the shift of the infrared cm-1 symmetric stretching band at 943 due to P(1), that is the phosphate more involved in Ca(4) coordination, which further supports the occupancy preference of strontium.”
Strontium and Zinc Substitution in -Tricalcium Phosphate: An X-ray Diffraction, Solid State NMR and ATR-FTIR Study DOI: 10.3390/jfb10020020 -
Phosphate (PO4) confidence 1.0
“The peak at cm-1 943 corresponds to P-O-N stretching [40].”
Chen 等 - 2021 - Synthesis of Novel Arginine-Based Flame Retardant DOI: 10.3390/molecules26123588 -
confidence 1.0
“et al increase of the Si-O-C band intensity near 965 Sonnenfeld assigned the absorption cm-1 band near 943 in the FTIR spectra of a plasma polymerized TEOS to Si-O-C symmetric stretching in Si-O-CH 2.”
Comparative study of bulk and surface compositions of plasma polymerized organosilicon thin films DOI: 10.1002/ppap.201900024.
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