What absorbs at 2300 cm⁻¹ in an FTIR spectrum?
A band near 2300 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 2300 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 |
|---|---|---|---|
| Hydroxyl (O-H) | 5 | 4 | 1.0 |
| Carbon dioxide | 4 | 4 | 1.0 |
| Carboxyl (COOH) | 3 | 3 | 1.0 |
| Amide | 3 | 3 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Ester | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| N c o | 1 | 1 | 1.0 |
| Amino acid | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| C#c | 1 | 1 | 1.0 |
| Thiol | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Silicon hydride | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 0 | 1.0 |
| Nitrile | 1 | 0 | 0.9 |
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 |
|---|---|---|---|
| MWCNT | 2300, 2876, 1430 | Hydroxyl (O-H) | 1 |
| graphite | 2300, 1640, 1326 | Hydroxyl (O-H) | 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 2300 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
-
Silicon (Si) confidence 1.0
“IR-spectra of the meso-PS films the absorption between 2300 Let us consider the possible mechanisms of the formation of cm(cid:2)1 and 2000 appears due to Si-H valence vibrations.”
Gorbanyuk 等 - 2006 - Porous silicon microstructure and composition char DOI: 10.1016/j.tsf.2005.08.188 -
Aromatic ring confidence 1.0
“showing Csp3 tions, resulting that the IR spectrum of the fluffy black C stretching at 8.2 µm, and aromatic C-H at 8.5 µm et al., material had larger atmospheric CO peaks at around 2300 (Gavilan 2016).”
Ito 等 - 2021 - Assessing the debris generated by the small carry- DOI: 10.2343/geochemj.2.0632 -
Hydroxyl (O-H) confidence 1.0
“On the other 6 6 cm(cid:2)1) m hand, the IR spectra for the O-H stretching region (2300 3800 indicate that hydrogen bonds between glucose molecules are Na+(cid:4)(cid:4)(cid:4)Cl(cid:2) significantly collapsed in the samples containing 5-15”
Kameda 等 - 2007 - Structure of amorphous NaCl-glucose system studied DOI: 10.1016/j.jnoncrysol.2007.02.025 -
Thiol confidence 1.0
“The peak between 2300 cm-1 nated their monodisperse phase with least possibilities of agand 2600 showed the presence of -SH functional group (-18.9 gregation.”
Removal of Cr(VI) by magnetic iron oxide nanoparticles synthesized from extracellular polymeric substances of chromium resistant acid-tolerant bacterium Lysinibacillus sphaericus RTA-01 DOI: 10.1007/s40201-019-00415-5 -
C#c confidence 1.0
“LLM confirmed rule peak-group candidate”
Kundu 等 - 2018 - Synthesis and characterization of iron and copper DOI: 10.1063/1.5051300 -
Carbon dioxide confidence 1.0
“The peak at 2300 was due to CO 2 adsorbed from the atmosphere and also possibility”
Conversion of residue biomass into value added carbon materials: utilisation of sugarcane bagasse and ionic liquids DOI: 10.1007/s10853-019-03800-5 -
Carbon dioxide confidence 1.0
“groups -COOH- (band at 1384 The peak at qe, мг/г cm-1 2300 corresponds to the peak of absorbed CO 2 25”
Yakovleva 等 - 2022 - SORPTION OF COPPER (II) CATIONS FROM AQUEOUS SOLUT DOI: 10.6060/ivkkt.20226505.6543 -
Carbon dioxide confidence 1.0
“This carbon dioxide, 0.18(cid:1) 0.4(cid:0) 0.85K+ 1.07H+ + + 10(OH) 2(Smectite) characteristic strong absorptions around 2000 and 2300 cm-1.”
Methanogenesis Potentials: Insights from Mineralogical Diagenesis, SEM and FTIR Features of the PermianMikambeni Shale of the Tuli Basin, Limpopo Provinceof South Africa DOI: 10.3390/min11060651
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