Carbonyl (C=O) — FTIR absorption peaks and assignments
These are the characteristic FTIR wavenumbers where Carbonyl (C=O) tends to absorb, compiled from published literature and ranked by supporting evidence. Each assignment is traceable to a source (DOI) and cross-validated against our 130,000+ reference spectra and knowledge graph.
Backed by 8 cited sources
Quick answer
Carbonyl (C=O) is usually assigned by looking for a recurring cluster of characteristic peaks rather than one exact textbook number. The table below shows where the literature most often places this group in FTIR, ranked by accumulated evidence.
Characteristic FTIR peaks for Carbonyl (C=O)
| Wavenumber (cm⁻¹) | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| 1700 | 168 | 141 | 1.0 |
| 1740 | 151 | 129 | 1.0 |
| 1730 | 151 | 128 | 1.0 |
| 1720 | 129 | 113 | 1.0 |
| 1735 | 99 | 89 | 1.0 |
| 1650 | 96 | 85 | 1.0 |
| 1750 | 78 | 68 | 1.0 |
| 1715 | 64 | 56 | 1.0 |
| 1710 | 63 | 53 | 1.0 |
| 1725 | 58 | 51 | 1.0 |
| 1640 | 57 | 49 | 1.0 |
| 1745 | 55 | 50 | 1.0 |
| 1630 | 55 | 48 | 1.0 |
| 1743 | 55 | 48 | 1.0 |
| 1660 | 51 | 45 | 1.0 |
| 1736 | 50 | 41 | 1.0 |
| 1600 | 49 | 44 | 1.0 |
| 1732 | 47 | 42 | 1.0 |
| 1744 | 46 | 40 | 1.0 |
| 1733 | 46 | 38 | 1.0 |
| 1724 | 45 | 40 | 1.0 |
| 1734 | 42 | 36 | 1.0 |
| 1737 | 40 | 33 | 1.0 |
| 1738 | 39 | 37 | 1.0 |
| 1741 | 39 | 37 | 1.0 |
| 1728 | 38 | 31 | 1.0 |
| 1655 | 35 | 31 | 1.0 |
| 1718 | 35 | 29 | 1.0 |
| 1723 | 35 | 28 | 1.0 |
| 1729 | 35 | 27 | 1.0 |
Showing the 30 best-supported peaks of 1094 total for Carbonyl (C=O).
Possible materials
Spectrum logic
A functional-group assignment becomes more confident when several expected bands appear together. Use this page to find the strongest-supported peaks, then confirm that the same sample exhibits a coherent pattern rather than a single isolated hit.
Real-world usage
These pages are useful for unknown material analysis, peak explanation in reports, polymer troubleshooting, and verifying whether a candidate material family is chemically plausible.
Common mistakes
- Using one functional-group page as a complete material verdict without checking the rest of the spectrum.
- Assuming the strongest band is always the most diagnostic one.
- Forgetting that processing, additives, aging, and mixtures can shift or broaden expected peaks.
Verification advice
Use DSC, GC-MS, or TGA when several material families share similar bands or when mixture effects make the FTIR assignment uncertain.
Literature behind these assignments
-
747 cm⁻¹ confidence 1.0
“Therefore, the ging band appears between 850 and regions, even though only one carbonyl group is present, prob746cm-1 747cm-1 in the infrared and in Raman is band at ably due to Fermi resonance.”
Arjunan 等 - 2007 - Fourier transform infrared and Raman spectral assi DOI: 10.1016/j.saa.2006.09.044 -
1735 cm⁻¹ confidence 1.0
“The new peak appears cm-1 at 1735 which indicates the presence of a C=O bond from carboxylic acid.”
Arizka 等 - 2019 - Synthesis and Physical Properties Characterization DOI: 10.1088/1757-899X/546/4/042004 -
2137 cm⁻¹ confidence 1.0
“The peak value at 2137, and 3391 The presence of alkyl, benzyl, methyl, 500 nm showed a characteristic wavelength for the synthesis and carbonyl groups in the molecule and the polar groups like -OH -NH of gold nanoparticles to increase in a”
Biogenic Synthesis of Gold Nanoparticle from Enicostema axillare and Their In Vitro Cytotoxicity Study Against MCF-7 Cell Line DOI: 10.1007/s12668-019-00656-6 -
1729 cm⁻¹ confidence 1.0
“Explicit assignment: 'The peak about 1729 cm-1 ... can be assigned to (C=O), the stretching mode of carbonyl groups'.”
Evaluation of microwave and magnetic properties of substituted SrFe12O19 and substituted SrFe12O19/multi-walled carbon nanotubes nanocomposites DOI: 10.1016/j.matchemphys.2013.08.045 -
1731 cm⁻¹ confidence 1.0
“Initiator Dicumyl Peroxide which are characterized by the appearance of wave 100 phr (33 g) cyclic natural rubber (CNR) is cm-1 number absorption peaks in the area of 1731 weighed, then CNR is slowly inserted into the internal (absorption o”
Aritonang 等 - 2019 - Grafting of Oleic Acid On Cyclic Natural Rubber Re DOI: 10.13005/ojc/350119 -
1672 cm⁻¹ confidence 1.0
“The most intense bands were the carbonyl peak at 1672 cm-1 and the benzene ring stretching at 1514, 1477, and 1392 cm-1.”
Armenta 等 - 2005 - FTIR approaches for diuron determination in commer DOI: 10.1021/jf050268f -
1695 cm⁻¹ confidence 1.0
“LLM confirmed rule peak-group candidate”
Ashri 等 - 2018 - Modified Dioscorea hispida starch-based hydrogels DOI: 10.1016/j.ijbiomac.2017.10.125 -
1746 cm⁻¹ confidence 1.0
“LLM confirmed rule peak-group candidate”
Ault 和 Pomeroy - 2012 - Quantitative Investigations of Biodiesel Fuel Usin DOI: 10.1021/ed101097n
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