What absorbs at 1118 cm⁻¹ in an FTIR spectrum?
A band near 1118 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 1118 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 |
|---|---|---|---|
| C-O single bond | 6 | 6 | 1.0 |
| Methoxy (OCH3) | 5 | 5 | 1.0 |
| Methacrylate | 5 | 5 | 1.0 |
| Acetate | 5 | 5 | 1.0 |
| Silicon-oxygen (Si-O) | 3 | 3 | 1.0 |
| Alkyl C-H | 3 | 3 | 1.0 |
| Carbohydrate | 3 | 2 | 1.0 |
| Silicon (Si) | 2 | 2 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| N-O bond | 2 | 2 | 1.0 |
| Borate | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| S eq o | 1 | 1 | 1.0 |
| Lignin | 1 | 1 | 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 |
|---|---|---|---|
| copper oxide | 1118, 624, 1686 | Methacrylate, Acetate | 1 |
| copper oxide nanoparticles | 1118, 624, 1317 | Methacrylate, Acetate | 1 |
| edible oils | 1118, 1743, 1064 | Methacrylate, Acetate | 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 1118 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
-
Carbohydrate confidence 1.0
“LLM confirmed rule peak-group candidate”
Eikje - 2011 - In vivo interstitial glucose characterization and DOI: 10.1117/12.874735 -
Alkyl C-H confidence 1.0
“LLM confirmed rule peak-group candidate”
Bromo-substituted blocked hexamethylene diisocyanate adduct: synthesis, characterization and applica DOI: 10.1080/10601325.2020.1845569 -
N-O bond confidence 1.0
“, a new vibration 1118cm(cid:4)1 not reported before in the literature was found at that has been assigned to the Ta-N-O linkage in the films.”
Microstructure and Thermal Diffusivity Investigations of RF-Sputtered Tantalum Nitride Films DOI: 10.1143/JJAP.41.5367 -
C-O single bond confidence 1.0
“The absorption band at 1118 was attributed To our knowledge, this is the first report showing this high value C OH skeletal vibration.”
Isolation and structural characterization of cellulose nanocrystals extracted from garlic straw residues DOI: 10.1016/j.indcrop.2016.04.060 -
N-O bond confidence 1.0
“cm(cid:2)1 was ascribed to NO absorption band at 1118 3”
Kayani 等 - 2015 - Characterization of Copper Oxide Nanoparticles Fab DOI: 10.1007/s11664-015-3867-5 -
Acetate confidence 1.0
“-CH2Bending 1138b 16 1147-1128 -C-O Stretching 1118a Stretching 17 1128-1106 -C-O”
Rapid evaluation of oxidised fatty acid concentration in virgin olive oil using Fourier-transform infrared spectroscopy and multiple linear regression DOI: 10.1016/j.foodchem.2010.06.054 -
Acetate confidence 1.0
“The Table 1 EDX result for the as-synthesized Pt@Cu nanostructures cm-1 peak at 1118 could be ascribed to C-O stretching A.”
Green synthesis of bimetallic Pt@Cu nanostructures for catalytic oxidative desulfurization of model oil DOI: 10.1007/s40097-017-0223-8 -
Acetate confidence 1.0
“two documented vibrations of -C-O at 1118 and 1138”
Parker 等 - 2014 - 60 MHz H-1 NMR spectroscopy for the analysis of ed DOI: 10.1016/j.trac.2014.02.006
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