What absorbs at 1488 cm⁻¹ in an FTIR spectrum?
A band near 1488 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 1488 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 |
|---|---|---|---|
| Alkene (C=C) | 3 | 3 | 1.0 |
| Aromatic ring | 3 | 3 | 1.0 |
| Alkyl C-H | 3 | 3 | 1.0 |
| Amide | 3 | 3 | 1.0 |
| Nucleic acid | 2 | 2 | 1.0 |
| Methyl | 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 |
| Acetate | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Metal oxygen | 1 | 1 | 1.0 |
| Chlorine | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Carbonate | 1 | 1 | 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 |
|---|---|---|---|
| PEG | 1488, 1650, 1342 | Alkyl C-H | 1 |
| silica | 1488, 1100, 1080 | Alkyl C-H | 1 |
| DNA | 1488, 1712, 1660 | 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 1488 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
-
C c single bond confidence 1.0
“While no change is observed in the carbonyl band at 1647 the cm-1 splitting of the aromatic C-C band at 1488 (highlighted by the dashed vertical lines in 4 Figure 3) is attributed to the attachment of the -SO 3H functional groups to the aro”
Vibrational spectroscopic study of pure and silica-doped sulfonated poly(ether ether ketone) membranes DOI: 10.1016/j.saa.2014.12.004 -
Chlorine confidence 1.0
“250 the out-of-plane bending C-H [3, 5, 7].The relative intensity metal (δ and/or δ N-Ag0) [8, 13] Cl-Ag0 1571cm-1 1488cm-1 of the band at and the band at indicates”
Benahmed 等 - 2018 - Spectroscopic Study of PolyanilineAgCl@Ag Nanocom DOI: 10.1155/2018/7320654 -
Metal oxygen confidence 1.0
“The absorption of the cytosine a merged broad absorption peak in the UV region was noticed in-plane vibration, adenine C7=N stretching, thymine C2=O at high [MCNT-TiO 2] due to the interactions between DNA stretching,andguanineC=Ostretching”
Dugasani 等 - 2019 - Optoelectronic properties of DNA thin films implan DOI: 10.1063/1.5063446 -
Amide confidence 1.0
“LLM confirmed rule peak-group candidate”
Modification of Thin Film Composite Pressure Retarded Osmosis Membrane by Polyethylene Glycol with Different Molecular Weights DOI: 10.3390/membranes12030282 -
Amide confidence 1.0
“1(a)} and it contains quinonoid (1582 benzenoid (1488 cm-1), cm-1), cm-1), C-N stretching (1304 aromatic stretching (817, 688 O-C stretching (1027 Ccm-1) cm-1).”
Mary 等 - 2023 - Synthesis, characterization and non-isothermal deg DOI: 10.21203/rs.3.rs-2849661/v1 -
Alkyl C-H confidence 1.0
“cm-1 peak at 1488 is owing to the C-H The peak at 1116 can be attributed to Si-O-Si”
Mustafov 等 - 2020 - Preparation and characterization of diatomite and DOI: 10.1038/s41598-020-70421-3 -
Acetate confidence 1.0
“Free DNA 3469-3430 1707, 1649 3469-3430 1237, 1098 1707 1649 1602 1484 DNA-AST 3469-3435 1714, 1647 3469-3435 1236, 1094 1714 1647 1604 1488 cm-1 cm-1 The vibrational frequency of C=O of the free DNA at 1707 shifted to 1714 in the”
Astragalin from Cassia alata Induces DNA Adducts in Vitro and Repairable DNA Damage in the Yeast Saccharomyces cerevisiae DOI: 10.3390/ijms13032846 -
Alkyl C-H confidence 1.0
“cm-1 of CTA-Mus was The transmission band at 1488 assigned to the asymmetric bending motion of the methyl”
Enhanced intercalation of organo-muscovite prepared via hydrothermal reaction at low temperature DOI: 10.1007/s12034-019-1931-0
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