What absorbs at 803 cm⁻¹ in an FTIR spectrum?
A band near 803 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 803 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) | 7 | 6 | 1.0 |
| Silicon (Si) | 5 | 4 | 1.0 |
| Siloxane (Si-O-Si) | 4 | 4 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| Boron nitrogen | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Alkene (C=C) | 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 |
|---|---|---|---|
| SiO | 803, 800, 1745 | Silicon-oxygen (Si-O), Siloxane (Si-O-Si), Silicon (Si) | 2 |
| polyaniline | 803, 1565, 1570 | Alkyl C-H | 1 |
| nanocomposites | 803, 1717, 1630 | Alkyl C-H | 1 |
| titanium dioxide | 803, 1716, 1724 | Alkyl C-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 803 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
-
confidence 1.0
“The spectra of L1-Cu to L4-Cu showed molecular ion peaks due to at m/z 803, 835, 871 and 904 which are equivalent to their molecular mass of respective compounds.”
Rational synthesis, biological screening of azo derivatives of chloro-phenylcarbonyl diazenyl hydroxy dipyrimidines/thioxotetrahydropyrimidines and their metal complexes DOI: 10.1016/j.heliyon.2022.e12492 -
confidence 1.0
“The PS-NPs-Ag gel was characterized by FTIR, observing a cm-1 cm-1 peak between 1000 and 1100 corresponding to Si-O-Si and a band at 803.33 typical cm-1 of siloxanes, as well as a band absorption at 3384 corresponding to NPs-Ag.”
Balvín Beltrán 等 - 2020 - Funcionalización del gel de polisiloxano con nanop DOI: 10.1038/srep35446 -
Silicon (Si) confidence 1.0
“The two medium size absorption cm-1 cm-1 bands around 803 and 468 are attributed to symmetric stretching and bending M cm-1 vibration of the Si-O-Si bond respectively, while the shoulder at 970 could be assigned to Si-OH group [22].”
Structural and optical investigations of Nd3+doped Y2O3-SiO2 nanopowder DOI: 10.1016/j.jallcom.2017.09.269 -
confidence 1.0
“cmfor Si-O-Si bending mode were observed at 452 and 521 Si-O-Si stretching (symmetric) mode at 777 1 cm-1 cm-1) and 803 and Si-O-Si stretching (asymmetric) (1020 bands were observed.”
Fabrication of sol-gel derived new quaternary silicate Bioglass S55P4 DOI: 10.1063/1.5089369 -
confidence 1.0
“2 The occurrence of polysaccharide, C=C bond, and Si-O stretching are represented by 1040, The occurrence of polysaccharide, C=C bond, and Si-O stretching are represented by 803, and 790 cm-1 peaks [28,49,50].”
Microstructural Characterization of Fibric Peat Stabilized with Portland Cement and Silica Fume DOI: 10.3390/ma16010018 -
Silicon (Si) confidence 1.0
“cm-1 absorbed water molecule on the silica The sharp peak band at 1099 is due to the Si-O-Si asymmetric cm-1 stretching vibration, whereas the band at 803 has been assigned to the network Si-O-Si symmetric bending”
Asmi 等 - 2016 - Synthesis and Characterisation of Composite based DOI: 10.1063/1.4945463 -
Alkyl C-H confidence 1.0
“The band at 803 cm-1 represented the stretching of C-H out-ofplane bending vibration [31].”
Bekhoukh 等 - 2021 - Development, Investigation, and Comparative Study DOI: 10.3390/polym13193344 -
Silicon (Si) confidence 1.0
“cm-1 The peak at 803 was attributed to Si-O.”
Khan 等 - 2021 - The Structural, Physical, and In Vitro Biological DOI: 10.14744/eej.2020.36349
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