What absorbs at 2890 cm⁻¹ in an FTIR spectrum?
A band near 2890 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 2890 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 |
|---|---|---|---|
| Alkyl C-H | 20 | 19 | 1.0 |
| Hydroxyl (O-H) | 6 | 6 | 1.0 |
| Oxygen heterocycle | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| N h | 1 | 1 | 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 |
|---|---|---|---|
| cellulose | 2890, 1735, 1650 | Alkyl C-H, 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 2890 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
-
Alkyl C-H confidence 1.0
“The bands located at ~2890 ~2010 cm-1 cm-1 and ~1640 are due to the stretching vibration of C-H, and CH groups, associated”
Oxygen vacancies and F+ centre tailored room temperature ferromagnetic properties of CeO2 nanoparticles with Pr doping concentrations and annealing in hydrogen environment DOI: 10.1016/j.jallcom.2020.156079 -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
Niaz 等 - 2020 - Alginate-caseinate based pH-responsive nano-coacer DOI: 10.1016/j.ijbiomac.2019.11.177 -
Hydroxyl (O-H) confidence 1.0
“It was observed that the absorption had a strong broad peak around cm(cid:1)1 cm(cid:1)1 μm-599 μm μm-849 μm 3320 for 425 and 3330 for 600 size classifications, O-H which corresponds to a different stretching mode of cm(cid:1)1 while the pe”
Influence of size classifications on the crystallinity index of Albizia gummifera cellulose DOI: 10.1016/j.heliyon.2022.e12019 -
Alkyl C-H confidence 1.0
“C-H the stretching of CH or CH groups of CS is at 3 2 2890cm-1.”
Almahamid 等 - 2022 - Application of Factorial Design and Response Surfa DOI: 10.1155/2022/1967606 -
Alkyl C-H confidence 1.0
“assigned to stretching vibrations of O-H and cm-1 N-H bond, peak at 2890 corresponding to saturated cm-1 C-H stretching vibration, peak at 2325 assigned to cm-1 C=O, band at 1617 corresponding to N=N azo”
Biodegradation and decolorization of azo dyes by adherent Staphylococcus lentus strain DOI: 10.1007/s13765-016-0169-4 -
Alkyl C-H confidence 1.0
“cm-1 The FR-lyocell fabric showed a band at 2890 on account of the C-H stretching cm-1 bands [43].”
Chen 等 - 2021 - Synthesis of Novel Arginine-Based Flame Retardant DOI: 10.3390/molecules26123588 -
Alkyl C-H confidence 1.0
“The band at 1705 2890 cm-1 originated from the C-H stretching vibrations of sp3 C-H bonds.”
Linking the Dynamic Changes in the In Vitro Antioxidant Activity of Carob Kibbles upon Roasting to the Chemical and Structural Changes Revealed by FTIR Spectroscopy DOI: 10.3390/antiox10122025 -
Alkyl C-H confidence 1.0
“Explicit assignment in text: 'cm-1 2890 is the stretching vibration of CH'”
Li 等 - 2020 - GlycerinNaOH Aqueous Solution as a Green Solvent DOI: 10.3390/polym12081735
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