What absorbs at 965 cm⁻¹ in an FTIR spectrum?
A band near 965 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 965 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 |
|---|---|---|---|
| Alkene (C=C) | 4 | 4 | 1.0 |
| Silicon-oxygen (Si-O) | 3 | 3 | 1.0 |
| Carbohydrate | 3 | 3 | 1.0 |
| Nucleic acid | 3 | 3 | 1.0 |
| Ammonium | 3 | 3 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| C-O single bond | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| Silanol (Si-OH) | 2 | 1 | 1.0 |
| Phosphate (PO4) | 2 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Lipid | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Siloxane (Si-O-Si) | 1 | 1 | 1.0 |
| Phosphorus | 1 | 1 | 1.0 |
| Sulfate (SO4) | 1 | 1 | 0.8 |
| Nitro (NO2) | 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 |
|---|---|---|---|
| PDMS | 965, 873, 1080 | Silicon-oxygen (Si-O) | 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 965 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
-
Nucleic acid confidence 1.0
“DNA-RNA I965 < I1055 < Imax and DNA-DNA interactions as were the most clearly observed in 3 BCC level DNA/RNA triad peak I965 < I1055 > Imax patients with high-leveled peaks of nucleic acids, that were presented as level DNA/RNA triad peak”
Eikje - 2011 - DNA-RNA, DNA-DNA, DNA-protein and protein-protein DOI: 10.1117/12.874692 -
Acetate confidence 1.0
“cm-1 group absorption peak between 1,500 and 1,400 the band between 1,542 cm-1 and 965 is attributed to vibration of the C-O, C-N, and C-N, demonstrating the cm-1 presence of organic acids, sugars, and ethanol in this area;”
Zhao 等 - 2021 - Evaluation of a strawberry fermented beverage with DOI: 10.7717/peerj.11974 -
Alkene (C=C) confidence 1.0
“cm-1 cm-1 Bands at 736 and 873 in OneFill suggested the presence of C-H bending, cm-1 cm-1 whereas bands at 965 showed C=C bending.”
Assiry 等 - 2023 - Microstructural and Elemental Characterization of DOI: 10.3390/app13074517 -
Ammonium confidence 1.0
“At 334 °C, new peaks appearing at 927 cm-1 and 965 cm-1 are attributed to NH3 absorptions, illustrating the decomposition of APP.”
The Effects of a Macromolecular Charring Agent with Gas Phase and Condense Phase Synergistic Flame Retardant Capability on the Properties of PP/IFR Composites DOI: 10.3390/ma11010111 -
Phosphate (PO4) confidence 1.0
“On the and 610 4 ν cm-1 other hand, the phosphate stretching mode band appeared at 965 and”
Cerium-doped hydroxyapatite nanoparticles synthesized by the co-precipitation method DOI: 10.2298/JSC150824007C -
Silicon-oxygen (Si-O) 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. -
Alkene (C=C) confidence 1.0
“Absorption cm-1 bands for terminal vinyl band stretching at 910 and terminal branched vinyl group band stretching at cm-1 965 were not observed indicating that the produced polymers do not contain any unreacted monomer or”
Gecim 和 Erkoc - 2020 - Gas phase polymerization of ethylene towards UHMWP DOI: 10.3906/kim-1907-48 -
Acetate confidence 1.0
“On the other hand, the highlighted wavenumbers at 965 cm-1 cm-1 958.59 and 963.19 for CS-Ag-H, CS-Ag-M and CS-Ag-L, respectively, could cm-1, cm-1 refer to the bonds or -C-O-Cstretch [49].”
Modification of Thin Film Composite Membrane by Chitosan–Silver Particles to Improve Desalination and Anti-Biofouling Performance DOI: 10.3390/membranes12090851
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