What absorbs at 1612 cm⁻¹ in an FTIR spectrum?
A band near 1612 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 1612 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 |
|---|---|---|---|
| Amide | 11 | 10 | 1.0 |
| Aromatic ring | 11 | 10 | 1.0 |
| Carboxyl (COOH) | 8 | 8 | 1.0 |
| Methacrylate | 6 | 6 | 1.0 |
| Acetate | 6 | 6 | 1.0 |
| Carbonyl (C=O) | 6 | 5 | 1.0 |
| Protein beta sheet | 6 | 5 | 1.0 |
| Alkene (C=C) | 5 | 4 | 1.0 |
| Ketone | 4 | 4 | 1.0 |
| Ester | 4 | 4 | 1.0 |
| N h | 4 | 4 | 1.0 |
| Hydroxyl (O-H) | 4 | 4 | 1.0 |
| Ring structure | 3 | 3 | 1.0 |
| Secondary amine | 3 | 3 | 1.0 |
| C-O single bond | 3 | 3 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| N-O bond | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Protein alpha helix | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 0.85 |
| C c single bond | 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 |
|---|---|---|---|
| rGO | 1612, 2358, 2930 | Methacrylate, Amide | 1 |
| hydrogels | 1612, 3281, 1700 | Amide, Methacrylate, Carboxyl (COOH) | 1 |
| CeO2 | 1612, 1554, 1630 | Methacrylate, Carboxyl (COOH) | 1 |
| quercetin | 1612, 1745, 1460 | Methacrylate, Amide, Carboxyl (COOH) | 1 |
| nanoparticles | 1612, 1732, 1647 | Methacrylate, Amide | 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 1612 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
-
confidence 1.0
“[31] the peak correspondbut were not observed at The DRIFTS peak at 1612 cm-1 ing to 1673 was assigned to the formation of bicarbonates could be due to the presence of adsorbed H 2O species formed during on a Cu/TiO catalyst and a TiO suppo”
Gaur 等 - 2013 - CO oxidation studies over cluster-derived AuTiO2 DOI: 10.1016/j.cattod.2012.10.029 -
Aromatic ring confidence 1.0
“[41-42] IR analysis of the whole plant extract of Gotu kola revealed that the presence of different functional groups ranging from O-H stretching, hydroxyl (3319.26 cm-1), C-H stretching, carbonyl (2921.96 cm-1), C=C stretching, aromatic ri”
Kumar 等 - 2021 - Centella asiatica mediated facile green synthesis DOI: 10.1016/j.inoche.2021.108865 -
Amide confidence 1.0
“1610cm-1 28.5-30.1◦ 1666 to or at C for the change in I or II band is the C O stretching and N H bending vibra1612/1673cm-1, peak intensity ratio of whereas the trantions, these vibrations are sensitive to hydrogen bonding and sition temper”
Lin 等 - 2005 - PHand thermal-dependent conformational transitio DOI: 10.1016/j.peptides.2004.11.005 -
Aromatic ring confidence 1.0
“SEM cm-1, CQ displayed N-H stretch at 3300 C-N stretch at cm-1, cm-1, C=C aromatic stretch at 1612 and C-Cl 1211 cm-1 peaks between 600 and 800 (Fig.”
Owonubi 等 - 2018 - Characterization and in vitro release kinetics of DOI: 10.1007/s40090-018-0139-2 -
Hydroxyl (O-H) confidence 1.0
“3400-3460cm-1 1612cm-1, The IR bands at are due to OH stretching vibrations.”
Synthesis of nanostructured CeO2 by chemical and biogenic methods: Optical properties and bioactivity DOI: 10.1016/j.ceramint.2020.02.204 -
Hydroxyl (O-H) confidence 1.0
“The bands coconut shell of graphite are cm-1 cm-1 cm-1 cm-1 3620 (OH stretch), 1612 (C = C aromatic), 1238 (stretching CO), and 829 (stretching”
Rukman 等 - 2019 - GO-Fe3O4 Nanocomposite from coconut shell Synthes DOI: 10.1088/1755-1315/217/1/012008 -
Hydroxyl (O-H) confidence 1.0
“In the cm-1 FTIR spectrum of Qu, absorbance at 3411 was cm-1 assigned to a free -OH bond vibration,at 1667 and cm-1 1612 were assigned to the stretching vibration of”
Setyawan 等 - 2018 - Improvement in vitro Dissolution Rate of Quercetin DOI: 10.22146/ijc.28511 -
Aromatic ring confidence 1.0
“cm-1 Based on the FTIR spectrum of PbP, a new peak can be identified at 1612.02 due to the aromatic C=C stretching vibration of benzene ring with a higher degree of substitution and intermolecular hydrogen bonding [12,”
Tan 等 - 2018 - Synthesis and Characterization of Polybenzoxazine DOI: 10.1063/1.5066866
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