What absorbs at 633 cm⁻¹ in an FTIR spectrum?
A band near 633 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 633 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.
Mogelijke functionele-groeptoewijzingen
| Functionele groep | Ondersteunende feiten | Geciteerde bronnen | Hoogste vertrouwen |
|---|---|---|---|
| Hydroxyl (O-H) | 3 | 3 | 1,0 |
| Chlorine | 2 | 2 | 1,0 |
| Phosphorus | 2 | 2 | 1,0 |
| Phosphate (PO4) | 2 | 2 | 1,0 |
| Metal oxygen | 2 | 2 | 1,0 |
| Secondary amine | 1 | 1 | 1,0 |
| C n single bond | 1 | 1 | 1,0 |
| Amide | 1 | 1 | 1,0 |
| Ring structure | 1 | 1 | 1,0 |
| C c single bond | 1 | 1 | 1,0 |
| Carboxyl (COOH) | 1 | 1 | 1,0 |
| S eq o | 1 | 1 | 1,0 |
| Alkyl C-H | 1 | 1 | 1,0 |
Ranglijst weerspiegelt cumulatief literatuurbewijs, niet één gezaghebbende regel. Bevestig altijd aan de hand van uw monsterecontext.
Possible materials
| Materiaal | Ondersteunende pieken | Overlapping groups | Geciteerde bronnen |
|---|---|---|---|
| kaolinite | 633, 3696, 693 | Hydroxyl (O-H), Phosphate (PO4) | 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 633 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.
Literatuur achter deze toewijzingen
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vertrouwen 1,0
“The FTIR spectra results show (Figure 6) that the absorption peaks at 485, 519, and 633 cm-1 are attributed to the Al-O structural vibration and are characteristic peaks of Al2O3, consistent with the standard infrared peaks of corundum [15]”
Study on Gemological Characteristics of Blue Sapphires from Baw-Mar Mine, Mogok, Myanmar DOI: 10.3390/cryst11111275 -
vertrouwen 1,0
“C-N The vibrations at 1462 and 1290 cm-1 are generated because of stretching and C-Cl bond is responsible for the bands at 605 and 633 cm-1 bending vibrations, while the (M-O) Er2O3 has a metal-oxygen bond shown at 557 cm-1 [29].”
New Hybrid PVC/PVP Polymer Blend Modified with Er2O3 Nanoparticles for Optoelectronic Applications DOI: 10.3390/polym15030684 -
Phosphate (PO4) vertrouwen 1,0
“Furthermore, the presence of the bands at 1093, 1033, 991, and 633 cm-1 is related to the phosphate”
Karami 等 - 2020 - Kinetics of Cross-Linking Reaction of Epoxy Resin DOI: 10.3390/polym12051157 -
Hydroxyl (O-H) vertrouwen 1,0
“This was also supported by the presence of peaks at 633 which indicates the presence of OH groups hydrogen-bonded with SO 3H (Malins et al., 2016).”
Synthesis and characterization of sulfonated activated carbon as a catalyst for bio-jet fuel production from biomass and waste plastics DOI: 10.1016/j.enconman.2014.07.007 -
Alkyl C-H vertrouwen 1,0
“Vibration of "additional" CH group corresponds to the band near 633 for A2 and S2 at 614 observed 2 CH2 group corresponds to the band near 633 cm-1 for A2 and S2 at 614 cm-1 observed also also in the FTIR spectra.”
Mikolaszek 等 - 2022 - Microscopic and Spectroscopic Imaging and Thermal DOI: 10.3390/polym14142888 -
vertrouwen 1,0
“cm-1 In the case of the sample JC-03 we find signals at 1175, 1129, 1088, and 987 corresponding to the symmetrical stretching vibration of S-O assigned to the presence of SO 4 cm-1 and at 633 and 608 to the bending vibration of SO 4.”
Nieto-Villena 等 - 2018 - Infrared Ellipsometry Analysis of Heritage Photogr DOI: 10.1080/00393630.2018.1476962 -
S eq o vertrouwen 1,0
“capacity Moreover, there is an enlarged band with a slight change at 582 cm-1 in the composite 55 removal beads, indicating the sulfonic acid group, due to the combination of the bands at 633 and”
Potential Application of Innovative Aspergillus terreus/ Sodium Alginate Composite Beads as Eco-Friendly and Sustainable Adsorbents for Alizarin Red S Dye: Isotherms and Kinetics Models DOI: 10.3390/microorganisms11051135 -
Phosphate (PO4) vertrouwen 1,0
“phosphate peaks at 633, 603 and 566 cm and decrease in 4 υ -1 For HAPS intensity.”
Wang 等 - 2012 - Formation and characterization of silica-coated HA DOI: 10.1515/secm-2011-0124
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