What absorbs at 2260 cm⁻¹ in an FTIR spectrum?
A band near 2260 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 2260 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 |
|---|---|---|---|
| N c o | 4 | 4 | 1.0 |
| Nitrile | 2 | 2 | 1.0 |
| Isocyanate | 2 | 1 | 1.0 |
| Chlorine | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Carbon dioxide | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| Silanol (Si-OH) | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Silicon hydride | 1 | 1 | 0.9 |
Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.
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 2260 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
-
Water (H2O) confidence 1.0
“sity of the SiH, SiOH and water peaks at 2260, 3650, and 800 °C directly on bare n-type wafers.”
Landheer 等 - 1998 - Fourier transform infrared spectroscopy of corona- DOI: 10.1116/1.589870 -
Silanol (Si-OH) confidence 1.0
“are related to the overtone of the fundamental band at 2260 and to the Si-OH stretching mode at 3670 Silica samples coming from”
Cova 等 - 2021 - Influence of the fiber drawing process on mechanic DOI: 10.1016/j.jnoncrysol.2020.120534 -
Carbon dioxide confidence 1.0
“Article cm-1 H 2O, a band at 3000 corresponding to CH 4, a band around cm-1 cm-1 2260 corresponding to CO 2, and a band around 2100 corresponding to CO.”
Du 等 - 2012 - Decarboxylation-Induced Cross-Linking of Polymers DOI: 10.1021/ma300751s -
N c o confidence 1.0
“The details of the FTIR bands are presented in 2260 -NCO stretching vibration Table 1.”
Du 等 - 2019 - Cure Kinetics of an Optical Polythiourethane with DOI: 10.1155/2019/8194379 -
Isocyanate confidence 1.0
“LLM confirmed rule peak-group candidate”
Jitaru 等 - 2016 - Polymer-graphene composites by the photocuring of DOI: 10.2298/JSC151218040J -
N c o confidence 1.0
“explicit assignment (absence)”
Polyurethane cationomers containing fluorinated soft segments with hydrophobic properties DOI: 10.1007/s00396-021-04819-4 -
Chlorine confidence 1.0
“9, the peaks at 2260 and 1158 were assigned to the Single ozonation and catalytic ozonation removed 2,4-D and Cl-”
Catalytic ozonation of toxic pollutants over magnetic cobalt-doped Fe3O4 suspensions DOI: 10.1016/j.apcatb.2012.01.020 -
N c o confidence 1.0
“cm-1 The absence of the -NCO band at about 2260 cm-1 shows that all -NCO groups were The absence of the -NCO band at about 2260 shows that all -NCO groups were converted to urethane and thiourethane groups [34].”
Synthesis and Characterization of New Polycarbonate-Based Poly(thiourethane-urethane)s DOI: 10.3390/polym14142933
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