What absorbs at 631 cm⁻¹ in an FTIR spectrum?
A band near 631 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 7 cited sources
Quick answer
A band near 631 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.
Iespējamie funkcionālo grupu piešķīrumi
| Funkcionālā grupa | Atbalstošie fakti | Citētie avoti | Augstākā pārliecība |
|---|---|---|---|
| Hydroxyl (O-H) | 4 | 4 | 1,0 |
| Amide | 1 | 1 | 1,0 |
| Phosphorus | 1 | 1 | 1,0 |
| Phosphate (PO4) | 1 | 1 | 1,0 |
| Siloxane (Si-O-Si) | 1 | 1 | 1,0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1,0 |
| Silicon (Si) | 1 | 1 | 1,0 |
| Metal oxygen | 1 | 1 | 0,95 |
Rangs atspoguļo uzkrātos literatūras pierādījumus, nevis vienu autoritatīvu noteikumu. Vienmēr apstipriniet atbilstoši parauga kontekstam.
Possible materials
| Materiāls | Atbalstošie pīķi | Overlapping groups | Citētie avoti |
|---|---|---|---|
| PVA | 631, 1660, 2930 | Hydroxyl (O-H), Amide | 1 |
| starch | 631, 1650, 1540 | Hydroxyl (O-H), Amide | 1 |
| glycerol | 631, 1585, 1630 | Hydroxyl (O-H) | 1 |
| polycaprolactone | 631, 1580, 1751 | Amide | 1 |
| apatite | 631, 3053, 1640 | Phosphate (PO4), Phosphorus, Amide | 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 631 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.
Literatūra aiz šiem piešķīrumiem
-
Hydroxyl (O-H) pārliecība 1,0
“3 cm-1, cm-1 The sharp narrow band at 630.92 634.47 and wide band at 3525.94 cm-1 are associated with the hydroxyl”
XRD and FTIR study of A&B type carbonated hydroxyapatite extracted from bovine bone DOI: 10.1063/1.5089399 -
Silicon (Si) pārliecība 1,0
“On the other hand, MMT nanoclays can be identified by stretching of Si-O-Si associated with bands of 631 cm-1 and 1075 cm-1 attributed to the bending of this group.”
Physical-Mechanical Behavior and Water-Barrier Properties of Biopolymers-Clay Nanocomposites DOI: 10.3390/molecules26216734 -
Phosphate (PO4) pārliecība 1,0
“There are two strong peaks due to the asymmetric ν4 bending mode of (PO4), a smaller peak at 631 cm-1 due to hycm-1 ν3 characteristic of phosphate groups at 1048 and 1087 attributed to asymmetric droxyl groups, a few weaker peaks due to car”
Archaeometric Investigations of the Chalcolithic Pottery from Topolița—Neamț County, Romania DOI: 10.3390/coatings13030488 -
Amide pārliecība 1,0
“Proteins, including the amide I peak at 1,631 cm-1, exhibit the strongest bands in the spectra depending on the secondary structure of the”
Macotpet 等 - 2020 - Attenuated total reflection Fourier transform infr DOI: 10.4142/jvs.2020.21.e16 -
Hydroxyl (O-H) pārliecība 1,0
“There is no evidence of any characteristic hydroxyl group vibrations (631 and 3572”
Mirkovic 等 - 2018 - Structural, Morphological and Electrical Propertie DOI: 10.2298/SOS1801095M -
Hydroxyl (O-H) pārliecība 1,0
“LLM confirmed rule peak-group candidate”
Characterization of PLA/PCL/Nano-Hydroxyapatite (nHA) Biocomposites Prepared via Cold Isostatic Pressing DOI: 10.3390/polym15030559 -
Metal oxygen pārliecība 0,95
“Explicit assignment: 'peak at 631cm-1 is attributed to the vibration of the Ti-O of anatase.'”
Sun 等 - 2006 - Preparation and gas-sensing property of a nanosize DOI: 10.1016/j.snb.2005.06.006
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