What absorbs at 687 cm⁻¹ in an FTIR spectrum?
A band near 687 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 687 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 |
|---|---|---|---|
| Metal oxygen | 3 | 3 | 1,0 |
| C-O single bond | 2 | 2 | 1,0 |
| Silicon-oxygen (Si-O) | 2 | 2 | 1,0 |
| Alkyl C-H | 2 | 2 | 1,0 |
| Hydroxyl (O-H) | 1 | 1 | 1,0 |
| Silicon (Si) | 1 | 1 | 1,0 |
| Methoxy (OCH3) | 1 | 1 | 1,0 |
| Methacrylate | 1 | 1 | 1,0 |
| Acetate | 1 | 1 | 1,0 |
| Aromatic ring | 1 | 1 | 1,0 |
| Carbonyl (C=O) | 1 | 1 | 1,0 |
| Carboxyl (COOH) | 1 | 1 | 1,0 |
| Bromine | 1 | 1 | 1,0 |
| Carbon bromine | 1 | 1 | 1,0 |
Rangs atspoguļo uzkrātos literatūras pierādījumus, nevis vienu autoritatīvu noteikumu. Vienmēr apstipriniet atbilstoši parauga kontekstam.
Possible materials
| Materiāls | Atbalstošie pīķi | Overlapping groups | Citētie avoti |
|---|---|---|---|
| polypropylene | 687, 1030, 1600 | Alkyl C-H, C-O single bond | 1 |
| TiO2 | 687, 1700, 1093 | Metal oxygen, Alkyl C-H, C-O single bond | 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 687 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
-
Metal oxygen pārliecība 1,0
“The bands cm-1 cm-1 at 300.9 and 347.19 correspond to M-O stretching mode of the octahedral group, and the cm-1 band at 686.66 corresponds to M-O stretching mode tetrahedral group [8, 11, 13].”
Deswardani 等 - 2017 - Study of Structural and Magnetic Properties of Sil DOI: 10.1088/1757-899X/202/1/012047 -
Carbon bromine pārliecība 1,0
“LLM confirmed rule peak-group candidate”
Furoida 和 Ulfa - 2019 - Synthesis of 3-(7-triphenylphosphonioheptyl)-2,6-d DOI: 10.1088/1757-899X/546/6/062008 -
Carboxyl (COOH) pārliecība 1,0
“The new peak at 1591 in acid equilibrated DHOA was assigned to the amide carbonyl 0.8 cm-1 group interacted with the HNO while the peak at 687 3 Intensity 0.7”
Verma 等 - 2018 - Structural investigations on uranium(VI) and thori DOI: 10.1039/C7NJ04460G. -
Metal oxygen pārliecība 1,0
“This agrees [PO with the phenomena in the quenched melts observed by Wong.[28] There is no evidence for Fe-O-P and Al-O-P bands in the present slags, as the latter type of bands 687.27cm-1 would result in stretch vibrations with Raman bands”
Wang 等 - 2015 - Effect of P2O5 and FetO on the Viscosity and Slag DOI: 10.1007/s11663-014-0270-1 -
Alkyl C-H pārliecība 1,0
“While the VIS regression coefficient showed a curve profile with a maximal contribution typical of the 8-hydroxyquinoline-Cd(II) complex [54], the FTIR regression coefficient profile included Kelex 100 characteristic IR vibrational bands at”
Determination of Cadmium (II) in Aqueous Solutions by In Situ MID-FTIR-PLS Analysis Using a Polymer Inclusion Membrane-Based Sensor: First Considerations DOI: 10.3390/molecules25153436 -
pārliecība 1,0
“of the -OH bonds and vibration via deformation of the bonds in adsorbed surface water molecules, of the -OH bonds and vibration via deformation of the bonds in adsorbed surface water molecules, cm-1 The peak located near 687 is characterist”
Metakaolin-Based Geopolymer with Added TiO2 Particles: Physicomechanical Characteristics DOI: 10.3390/coatings7120233 -
Silicon (Si) pārliecība 1,0
“The bands at 744 and 687 cm-1 are attributed to the perpendicular Si-O stretching vibration.”
Morphology and Selected Properties of Modified Potato Thermoplastic Starch DOI: 10.3390/polym15071762 -
C-O single bond pārliecība 1,0
“The peak observed at 687 represents C-OH out-of-plane, denoting the presence of cellulose [91-94].”
Characterization of Thermo-Mechanical and Chemical Properties of Polypropylene/Hemp Fiber Biocomposites: Impact of Maleic Anhydride Compatibilizer and Fiber Content DOI: 10.3390/polym15153271
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