What absorbs at 500 cm⁻¹ in an FTIR spectrum?
A band near 500 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 500 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 |
|---|---|---|---|
| Metal oxygen | 22 | 20 | 1.0 |
| Methoxy (OCH3) | 11 | 10 | 1.0 |
| Methacrylate | 11 | 9 | 1.0 |
| Acetate | 11 | 9 | 1.0 |
| Hydroxyl (O-H) | 10 | 8 | 1.0 |
| Alkyl C-H | 9 | 8 | 1.0 |
| Silicon-oxygen (Si-O) | 8 | 8 | 1.0 |
| C-O single bond | 8 | 7 | 1.0 |
| Carboxyl (COOH) | 8 | 6 | 1.0 |
| Siloxane (Si-O-Si) | 6 | 6 | 1.0 |
| Phosphate (PO4) | 5 | 5 | 1.0 |
| Silicon (Si) | 5 | 5 | 1.0 |
| C c single bond | 4 | 4 | 1.0 |
| Amide | 4 | 3 | 1.0 |
| Bromine | 2 | 2 | 1.0 |
| Carbon bromine | 2 | 2 | 1.0 |
| Water (H2O) | 2 | 2 | 1.0 |
| Phosphorus | 2 | 2 | 1.0 |
| Methyl | 2 | 2 | 1.0 |
| N h | 2 | 2 | 1.0 |
| Aromatic ring | 2 | 1 | 1.0 |
| N-O bond | 2 | 1 | 1.0 |
| Oxygen heterocycle | 1 | 1 | 1.0 |
| Silanol (Si-OH) | 1 | 1 | 1.0 |
| Sulfur | 1 | 1 | 1.0 |
| Chlorine | 1 | 1 | 1.0 |
| S eq o | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Silicon carbon | 1 | 1 | 1.0 |
| Metalloid oxygen | 1 | 1 | 1.0 |
| Ketone | 1 | 0 | 1.0 |
| Ester | 1 | 0 | 1.0 |
| Carbonyl (C=O) | 1 | 0 | 1.0 |
| Anhydride | 1 | 0 | 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 |
|---|---|---|---|
| Zinc Oxide Nanoparticles | 500, 1744, 1627 | Acetate, Methacrylate, Methoxy (OCH3) | 1 |
| nanocomposite | 500, 2921, 3300 | Methacrylate, Acetate, Metal oxygen | 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 500 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
“The region at 1053 cm-1 corresponds to -C-O-C stretching bonds whereas the spectra with wavenumber below 500 cm-1 correspond to the presence of metal oxides, and the stretching at 485 cm-1 conCatalysts2021,11,1507 8of20 firms the presence o”
Synthesis and Characterization of Zinc Oxide Nanoparticles Using Acacia caesia Bark Extract and Its Photocatalytic and Antimicrobial Activities DOI: 10.3390/catal11121507 -
Acetate confidence 1.0
“The exothermic peak at 500 by hydrolytically stable -Si-(CH 3) groups present in HMDS corresponds to the critical temperature of -(CH 3) groups at 3 3 and TMCS, according to the chemical reactions (2) and (3) which they get oxidized leaving”
Bhagat 等 - 2007 - Rapid synthesis of water-glass based aerogels by i DOI: 10.1016/j.apsusc.2006.07.016 -
C c single bond confidence 1.0
“1000 C-Ag C-C Plasmon peak 500 Si-O C=O”
Synthesis and Characterization of Silicon Nanowires by Electroless Etching DOI: 10.1007/s11665-018-3179-z -
confidence 1.0
“FTIR analysis confirmed a successful doping procm-1 energy to migrate to the lowest-empty levels within the cess, where the peak at 500 represents the Ti-O bond.”
Structural and optical characteristics of Ti-doped ZnO nanorods deposited by simple chemical bath deposition DOI: 10.1007/s10854-017-6905-7 -
Hydroxyl (O-H) confidence 1.0
“spectra show three spectral regions of particular interest: cm-1, the the fingerprint region between 400 and 1,500 cm-1 that corresponds to region between 2,700 and 3,100 C─H the bonds in organic compounds, and the OH cm-1.”
Combining Fourier transform infrared and Raman spectroscopies with Gaussian deconvolution: An improved approach for the characterization of emeralds DOI: 10.1002/jrs.5810 -
Phosphate (PO4) confidence 1.0
“after Immersion in Phosphate Solution The FTIR spectrum of the undoped glass shows composite and connected vibrational peaks extending from 500 to about cm-1 1650 and followed by the near IR spectrum extending Figure 7 illustrates the FTIR”
Bioactivity Behavior of Multicomponent (P2O5 –B2O3- SiO2-Na2O-CaF2) Glasses Doped with ZnO, CuO or Ag2O and their Glass-Ceramics DOI: 10.1007/s12633-020-00571-6 -
confidence 1.0
“The peak at around 500 in the FTIR studies was used to investigate the extraction of chiZnO NPs spectra is due to Zn-O vibration band whereas in”
Green Synthesis, Structural Characterization and Photocatalytic Activities of Chitosan-ZnO Nano‐composite DOI: 10.1007/s10904-021-01988-1 -
confidence 1.0
“of calcium, which showed a weak positive correlation with To this end, fertilized and control samples were scanned 500cm1.”
Hssaini 等 - 2022 - Do Pollination and Pollen Sources Affect Fig Seed DOI: 10.1155/2022/3969165
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