What absorbs at 1045 cm⁻¹ in an FTIR spectrum?
A band near 1045 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 1045 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 | 22 | 20 | 1.0 |
| Methacrylate | 20 | 19 | 1.0 |
| Acetate | 20 | 19 | 1.0 |
| Methoxy (OCH3) | 19 | 18 | 1.0 |
| Hydroxyl (O-H) | 10 | 9 | 1.0 |
| Phosphate (PO4) | 7 | 7 | 1.0 |
| Alkyl C-H | 7 | 6 | 1.0 |
| Carbohydrate | 6 | 6 | 1.0 |
| Amide | 4 | 4 | 1.0 |
| Carboxyl (COOH) | 3 | 3 | 1.0 |
| N h | 3 | 2 | 1.0 |
| Secondary amine | 3 | 2 | 1.0 |
| Lignin | 2 | 2 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Ester | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| C n single bond | 2 | 2 | 1.0 |
| Phosphorus | 1 | 1 | 1.0 |
| Silicon carbon | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Boron nitrogen | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| N-O bond | 1 | 1 | 1.0 |
| Fluorine (C-F) | 1 | 1 | 1.0 |
| Siloxane (Si-O-Si) | 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 |
|---|---|---|---|
| chitosan | 1045, 1650, 1655 | Acetate, Methacrylate, C-O single bond | 1 |
| CuO | 1045, 453, 1000 | Methacrylate, Acetate, Methoxy (OCH3) | 1 |
| polycaprolactone | 1045, 1580, 1751 | Methacrylate, Acetate, Methoxy (OCH3) | 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 1045 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
-
Carbohydrate confidence 1.0
“The bands at 1045 and have been linked with order/crystallinity and amorphous regions in starch, 3.4.”
Allomorph distribution and granule structure of lotus rhizome C-type starch during gelatinization DOI: 10.1016/j.foodchem.2013.07.091 -
confidence 1.0
“Z.Mahmoodetal./SpectrochimicaActaPartA65(2006)445-452 451 558cm-1are 1063cm-1 to MCO bending vibration and band observed at and the C-F stretching bands are found at 1045 and”
Mahmood 等 - 2006 - Comparative vapour phase FTIR spectra and vibratio DOI: 10.1016/j.saa.2005.11.024 -
Acetate confidence 1.0
“asymmetricandsymmetricstretchingvibrations,respectively.The bands for C-O and sulphonate group are also present at 1225 and 1045cm-1, respectively.”
Micelle based synthesis of cobalt ferrite nanoparticles and its characterization using Fourier Transform Infrared Transmission Spectrometry and Thermogravimetry DOI: 10.1016/j.matchemphys.2010.06.029 -
Alkyl C-H confidence 1.0
“aliphatic bending of the organic compounds in the extract 1045.38cm-1 [30].”
Rotich 等 - 2022 - FT-IR Analysis of Beta vulgaris Peels and Pomace D DOI: 10.1155/2022/2233414 -
Carbohydrate confidence 1.0
“Additionally, the cm-1) other two glycogen bands (1045 and 1025 shifted in peak 1 A.”
Shi 等 - 2018 - Biochemical alterations of Candida albicans during DOI: 10.1039/c8an01452c -
Acetate confidence 1.0
“cm-1) bending vibration (assigned to 1580 when increasing the plasma exposure time, bending vibration (assigned to 1580 cm-1) when increasing the plasma exposure time, cm-1) while significant increase in C-O-C stretching bands (1295, 1245,”
Plasma-Induced Graft Polymerization of Polyethylenimine onto Chitosan/Polycaprolactone Composite Membrane for Heavy Metal Pollutants Treatment in Industrial Wastewater DOI: 10.3390/coatings12121966 -
N-O bond confidence 1.0
“The peaks due to the stretch vibrations in NO at 1410 3 -1360cm-1 1045cm-1 are evident [13].”
Zhang 等 - 2013 - Synthesis and Characterization of Bi2Al4O9 Powders DOI: 10.4028/www.scientific.net/AMR.624.34 -
Hydroxyl (O-H) confidence 1.0
“cm-1, cm-1, cm-1, cm-1, cm-1, cm-1 1736 1621 1560 1396 1215 and 1045 related to OH cm-1, 1736 cm-1, 1621 cm-1, 1560 cm-1, 1396 cm-1, 1215 cm-1, and 1045 cm-1 related to OH sp2-hybridized groups, the stretching of carboxylic acid groups, C g”
Effect of rGO wt.% on the Preparation of rGO/CuO Nanocomposites at Different Test Periods and Temperatures DOI: 10.3390/cryst12101325
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