What absorbs at 1021 cm⁻¹ in an FTIR spectrum?
A band near 1021 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 1021 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 |
|---|---|---|---|
| C-O single bond | 13 | 13 | 1.0 |
| Methacrylate | 11 | 11 | 1.0 |
| Acetate | 11 | 11 | 1.0 |
| Methoxy (OCH3) | 10 | 10 | 1.0 |
| Phosphate (PO4) | 5 | 5 | 1.0 |
| Silicon-oxygen (Si-O) | 4 | 4 | 1.0 |
| Amide | 4 | 4 | 1.0 |
| Hydroxyl (O-H) | 4 | 4 | 1.0 |
| Siloxane (Si-O-Si) | 2 | 2 | 1.0 |
| Metal oxygen | 2 | 2 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Ester | 2 | 2 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| Phosphorus | 1 | 1 | 1.0 |
| N n bond | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Thiocarbonyl | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
| Oxygen heterocycle | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| S eq o | 1 | 1 | 1.0 |
| Sulfonyl | 1 | 1 | 1.0 |
| Carbonate | 1 | 1 | 1.0 |
| Carbohydrate | 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 |
|---|---|---|---|
| PVA | 1021, 1660, 2930 | Acetate, Methacrylate, C-O single bond | 1 |
| polysulfone | 1021, 1700, 2941 | Methacrylate, Acetate, C-O single bond | 1 |
| Polyethylene | 1021, 1737, 1720 | Methacrylate, Acetate, Methoxy (OCH3) | 1 |
| montmorillonite | 1021, 1637, 523 | Methacrylate, Acetate | 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 1021 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
-
Acetate confidence 1.0
“As a reference band 1021 was chosen which is assigned to the C-O stretching vibration of carbohydrates, such as the”
FTIR as an easy and fast analytical approach to follow up microbial growth during fungal pretreatment of poplar wood with Phanerochaete chrysosporium DOI: 10.1016/J.MIMET.2018.01.004 -
Carbonate confidence 1.0
“At 24 h (Figure 5A), in all thicknesses, nesses, the behavior is similar: a peak corresponding to the presence of OH bonds, folthe behavior is similar: a peak corresponding to the presence of OH bonds, followed cm-1, lowed by a peak corresp”
Remineralization Potential of Three Restorative Glass Ionomer Cements: An In Vitro Study DOI: 10.3390/jcm12062434 -
confidence 1.0
“2014 1041 Si-O stretching 1021 1027 1035”
Hayati-Ashtiani - 2012 - Use of FTIR Spectroscopy in the Characterization o DOI: 10.1080/02726351.2011.615895 -
Hydroxyl (O-H) confidence 1.0
“A peak at cm-1 1021 was detected for alginate, FHO, and FHO-A which can be assigned to O-H bending [26].”
Kim 等 - 2019 - The Application of Alginate Coated Iron Hydroxide DOI: 10.3390/app9183835 -
Siloxane (Si-O-Si) confidence 1.0
“Peak at 1021 cm-1 assigned to symmetric vibration of Si-O-Si.”
Thermal, Rheological, Mechanical and Morphological Behavior of High Density Polyethylene and Carboxymethyl Cellulose Blend DOI: 10.1007/s10924-016-0880-6 -
Acetate confidence 1.0
“The PHP method proved to be a convenient and reliable cm-1 The peak at 1021 is due to C-O bending vibration and method of quantifying the presence of (cid:533).CD on the functionalised cm-1 the absorption band at 1152 is due to C-O-C (alkyl”
A new approach for the functionalisation of polysulfone with β-cyclodextrin DOI: 10.1088/2053-1591/ab35f3 -
Sulfonyl confidence 1.0
“adsorption peak due to C-O stretching at 1105 By comparing spectra of polymer blend membrane with that for GA-cross-linked PVA membrane, new absorption bands are cm-1 noticed at 1021 and 1112 due to the symmetric and asymmetric O=S=O stretc”
Highly Conductive Polyelectrolyte Membranes Poly(vinyl alcohol)/Poly(2-acrylamido-2-methyl propane sulfonic acid) (PVA/PAMPS) for Fuel Cell Application DOI: 10.3390/polym13162638 -
Acetate confidence 1.0
“The displayed frequencies for HPβCD were identified at 3332.04 and 1020.70 cm-1 The phase solubility analysis was executed to examine the solubility of SA in HPβCD that represent the stretching vibration of the C-O-C and O-H moiety.”
Hydroxypropyl–Cyclodextrin for Delivery of Sinapic Acid via Inclusion Complex Prepared by Solvent Evaporation Method DOI: 10.3390/pr10102046
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