What absorbs at 947 cm⁻¹ in an FTIR spectrum?
A band near 947 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 947 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 |
|---|---|---|---|
| Silicon-oxygen (Si-O) | 2 | 2 | 1.0 |
| Silanol (Si-OH) | 2 | 2 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| Silicon (Si) | 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 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| Siloxane (Si-O-Si) | 1 | 1 | 1.0 |
| N-O bond | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 0.9 |
| Metal oxygen | 1 | 0 | 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 |
|---|---|---|---|
| SiO2 | 947, 1739, 699 | Silicon-oxygen (Si-O), Alkyl C-H, Silicon (Si) | 1 |
| membrane | 947, 1316, 2927 | Alkyl C-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 947 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
“lizing the reaction of acrylic acid with DGE introduin the FTIR spectra of BHAPP, Figure 1, were those ces a flexible aliphatic chain containing three cm(cid:1)1, corresponding to the carbonyl group at 1725 C¼¼C hydroxyl groups between the”
Synthesis, characterization, and curing of a new acrylate-based dental restorative resin DOI: 10.1002/app.28683 -
C c single bond confidence 1.0
“Likewise, skeletal C-C vibrations cm-1 cm-1, between 947 and 1161 vanished completely.”
Wetting, Solubility and Chemical Characteristics of Plasma-Polymerized 1-Isopropyl-4-Methyl-1,4-Cyclohexadiene Thin Films DOI: 10.3390/coatings4030527 -
Silanol (Si-OH) confidence 1.0
“2 cm-1 new absorption peaks, such as 478 of (Si-O) rocking between 20 nm to 190 nm surrounded by the SiO shells 2 cm-1 of (Si-OH) asymmetric vibration that vibration and 0947 between 20 nm to more than 600 nm, as shown in Figures 4 reflecte”
Al-Bermany 等 - 2023 - Effect of green synthesis bimetallic Ag@SiO2 core- DOI: 10.1007/s12633-023-02332-7 -
N-O bond confidence 1.0
“Peak assignment Modified acrylic fibers RO16 Modified acrylic fibers dyed with RO16 N-O stretching, amidoxime 947”
El-Shishtawy 等 - 2014 - Nucleophilic Addition of Reactive Dyes on Amidoxim DOI: 10.1155/2014/305930 -
Siloxane (Si-O-Si) confidence 1.0
“1383 cm-1 700-800 are attributed to vibrations due to 1649 800449 Si-O-Si symmetric stretching of bridging oxy947”
Hamzawy 等 - 2023 - Glasses and Glass-Ceramics from Li2O-KF-TiO2-SiO2 DOI: 10.1007/s12633-023-02531-2 -
Alkyl C-H confidence 1.0
“cm(cid:0) 1 1 × × q b (C-O tion), 1089 and 1030 stretching vibration), and 947 m,CS Cu e,Cu Cu(II) : = For q (11) cm(cid:0) e,Cu 1 C1/nHg (C-H deformation) (Mo et al., 2020).”
Investigation of mercury (II) and copper (II) sorption in single and binary systems by alginate/polyethylenimine membranes DOI: 10.1016/j.carbpol.2020.117588 -
Silanol (Si-OH) confidence 1.0
“-Si-O-Siasymmetric stretching (high crosslinking degree) 1055 -Si-O-Siasymmetric stretching (surface groups, low crosslinking degree) ~ 960-950 -Si-OH stretching 947”
A Process Analytical Concept for In-Line FTIR Monitoring of Polysiloxane Formation DOI: 10.3390/polym12112473 -
Silicon (Si) confidence 1.0
“Besides, the bands at 434, cm-1 769 and 947 were due to infrared absorption by the Si-O bond.”
Zaid 等 - 2017 - Effect of Sintering on Crystallization and Structu DOI: 10.2298/SOS1704409Z
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