What absorbs at 1606 cm⁻¹ in an FTIR spectrum?
A band near 1606 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 1606 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 |
|---|---|---|---|
| Aromatic ring | 11 | 10 | 1.0 |
| Ring structure | 9 | 9 | 1.0 |
| Amide | 8 | 8 | 1.0 |
| Alkene (C=C) | 8 | 7 | 1.0 |
| Carboxyl (COOH) | 6 | 6 | 1.0 |
| Hydroxyl (O-H) | 6 | 5 | 1.0 |
| Methacrylate | 5 | 5 | 1.0 |
| Carbonyl (C=O) | 5 | 4 | 1.0 |
| N h | 4 | 4 | 1.0 |
| Ketone | 4 | 4 | 1.0 |
| Ester | 4 | 4 | 1.0 |
| Acetate | 4 | 4 | 1.0 |
| Water (H2O) | 4 | 3 | 1.0 |
| C c single bond | 3 | 3 | 1.0 |
| Alkyl C-H | 3 | 3 | 1.0 |
| C=n | 2 | 2 | 1.0 |
| Protein | 2 | 2 | 1.0 |
| Lignin | 2 | 2 | 1.0 |
| Amino acid | 2 | 2 | 1.0 |
| Metal hydroxyl | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
| Nitrogen heterocycle | 1 | 1 | 1.0 |
| Aldehyde (CHO) | 1 | 1 | 1.0 |
| Lewis acid site | 1 | 1 | 1.0 |
| Adsorbed carbon monoxide | 1 | 1 | 1.0 |
| Carbonate | 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 |
|---|---|---|---|
| AgNPs | 1606, 1232, 1048 | Amide | 1 |
| dentin | 1606, 575, 1740 | 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 1606 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
-
Ring structure confidence 1.0
“IntheIberiansamplethecharacteristicsignalsofthearomatic 1606cm-1, rings, especially those of symmetric ring stretch 700cm-1) although out-of-plane ring bend loop (822, 755 and are even stronger probably due to the higher level of dehydroFig”
Font 等 - 2007 - Fourier transform infrared spectroscopy as a suita DOI: 10.1016/j.aca.2007.07.021 -
Adsorbed carbon monoxide confidence 1.0
“peaks at 1606, 1356, 1492, 1465, and 1433 decreased with the commercial catalyst, the bridging CO peaks at For time.”
Gaur 等 - 2013 - CO oxidation studies over cluster-derived AuTiO2 DOI: 10.1016/j.cattod.2012.10.029 -
confidence 1.0
“resin matrices at 1606 The N-H deformation stretching of urethane dimethacrylate cm-1.”
Structural, Physical, and Mechanical Analysis of ZnO and TiO2 Nanoparticle-Reinforced Self-Adhesive Coating Restorative Material DOI: 10.3390/ma14247507 -
Acetate confidence 1.0
“AgNPs exhibited prominent peaks at 2360.7, 1606.2, 1095.6 and 785.9 The spectral peak observed at 1606.2, assigned to stretching vibration (C=O) in carbonyl compounds characterized by the presence of major constituents of flavonoids and ter”
Kumar 等 - 2017 - Photo-induced and phytomediated synthesis of silve DOI: 10.1016/j.jphotobiol.2017.04.022 -
Aromatic ring confidence 1.0
“The differences in (C@C) (2800-3000cm(cid:2)1) and the aromatic carbon peak at absorbance of the aliphatic stretching bands 1606cm(cid:2)1areveryobvious.ComparedtothatoftheDraytonsample(0.7%Sand15%O),thetelocollinite of the Cranky Corner co”
Chemical functionalities of high and low sulfur Australian coals: A case study using micro attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectrometry DOI: 10.1016/j.orggeochem.2010.02.016 -
C c single bond confidence 1.0
“cm-1 cm-1 cm-1 1633 and 1048 and peak broadening at 1606 due to C-C multiple stretching [26, A 27].”
Srivastava 等 - 2018 - Studies on the structural changes during curing of DOI: 10.1016/j.saa.2017.06.066 -
Aromatic ring confidence 1.0
“There is a strong and sharp absorption peak at 1606 E cm-1, owing to the benzene ring C=C skeleton stretching vibration of aromatics, T cm-1-900 cmindicating that there are many aromatics in CTHIS [27].”
Pyrolysis characteristics of ethanol swelling Shendong coal and the composition distribution of its coal tar DOI: 10.1016/j.jaap.2018.12.012 -
Alkyl C-H confidence 1.0
“cm-1 and 1606 peaks correspond to aliphatic and aromatic C=C bonds, respectively, and the relation between its absorbance peak intensity (R) is in Table 2.”
Abreu 等 - 2016 - Effect of Non-Thermal Argon Plasma on Bond Strengt DOI: 10.1590/0103-6440201600914
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