What absorbs at 1820 cm⁻¹ in an FTIR spectrum?
A band near 1820 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 2 cited sources
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Literature behind these assignments
-
Acetate confidence 1.0
“cm-1 of the peak at 1820 This is because the first peak at 1820 is the C=O stretching cm-1 vibration of CAC, while the second peak at 1783 is the result of Fermi resonance”
Zhu 等 - 2021 - Separation and Rectification of Chloroacetyl Chlor DOI: 10.3390/pr9020287 -
Carbonyl (C=O) confidence 0.6
“Text says 'weak band at 1820 is strongly polarised out of plane' typical for carbonyl.”
Microsoft Word - Frogley et al Polarised infrared microspectroscopy of edge-oriented graphene oxide papers.docx DOI: 10.1038/srep00085
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