What absorbs at 1003 cm⁻¹ in an FTIR spectrum?
A band near 1003 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 1003 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 |
|---|---|---|---|
| Silicon-oxygen (Si-O) | 3 | 3 | 1.0 |
| Methacrylate | 3 | 3 | 1.0 |
| C-O single bond | 3 | 3 | 1.0 |
| Acetate | 3 | 3 | 1.0 |
| Phosphate (PO4) | 2 | 2 | 1.0 |
| Siloxane (Si-O-Si) | 2 | 2 | 1.0 |
| C c single bond | 2 | 2 | 1.0 |
| Methoxy (OCH3) | 2 | 2 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| Silicon (Si) | 2 | 2 | 1.0 |
| Amino acid | 1 | 1 | 1.0 |
| Phosphorus | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Amine primary | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| N h | 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 |
| Metal oxygen | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Metal oxo | 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 |
|---|---|---|---|
| polypyrrole | 1003, 1700, 400 | Methacrylate, Acetate | 1 |
| lignin | 1003, 1035, 1510 | Methacrylate, Acetate, C-O single bond | 1 |
| polypropylene | 1003, 1030, 1600 | Methacrylate, Acetate, C-O single bond | 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 1003 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
-
Metal oxo confidence 1.0
“Explicitly stated: 'peaks at 1003 and 956 assigned respectively to V5+=O and V4+=O'”
Nagaraju - 2013 - Ultra Long Single Crystalline Na0.3V2O5 Nanofibers DOI: 10.5935/0103-5053.20130213 -
Silicon (Si) confidence 1.0
“Strong peaks at 1060 and 1003 cm-1 were observed, characteristic of the Si-O-Si stretching.”
Alassod 等 - 2021 - PolypropyleneLigninPOSS Nanocomposites Thermal DOI: 10.3390/ma14143950 -
Silicon (Si) confidence 1.0
“sample displays two discrete sharp bands at 1003 and 1088 (presumably due to in-plane and sample displays two discrete sharp bands at 1003 and 1088 cm-1 (presumably due to in-plane and νSi-O, out-of-plane respectively), suggesting great par”
The Nature of Laponite: Pure Hectorite or a Mixture of Different Trioctahedral Phases? DOI: 10.3390/min8080314 -
Acetate confidence 1.0
“saccharide band cm-1 524cm-1 cm-1 cm-1 1003 for for 995 for C-O band 995 for C-O band”
Exosomes isolated from two different cell lines using three different isolation techniques show variation in physical and molecular characteristics DOI: 10.1101/2020.06.06.122952 -
confidence 1.0
“ν(CS)δ(CNS) vibrational mode in complex 2”
Ni-thiosaccharinate complexes: synthesis, characterization and DFT studies. Biological properties as superoxide dismutase mimetics and as anti-carcinogenic agents DOI: 10.1016/j.ica.2019.04.040 -
Alkene (C=C) confidence 1.0
“stretching (1066 -CH-O-CHstretching (1003 and =C-H bending (949 cm-1) and = C-H bending (949 cm-1).”
Substantial Proton Ion Conduction in Methylcellulose/Pectin/Ammonium Chloride Based Solid Nanocomposite Polymer Electrolytes: Effect of ZnO Nanofiller DOI: 10.3390/membranes12070706 -
Metal oxygen confidence 1.0
“Fe-O vibrational 1003cm-1 modes in FeOOH were ascribed at 1640, 1363, and for the PPy NPs peak at due to the out-of-plane 1141cm-1 in the PFFs spectra while there were no peaks in bending C-H bond [31, 34-36].”
Diauudin 等 - 2020 - Preparation and Characterisation of Polypyrrole-Ir DOI: 10.1155/2020/8762969 -
Acetate confidence 1.0
“By comparing the spectra of SUCFs with the copolymer, it was found that spectra of SUCFs possess peaks related to NH symmetrical stretching at 3430-3336 cm-1, C=O stretching at 1675 cm-1, stretching in NH or NH2 at 1590 cm-1, shortening of”
Degradable Slow-Release Fertilizer Composite Prepared by Ex Situ Mixing of Inverse Vulcanized Copolymer with Urea DOI: 10.3390/agronomy12010065
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