What absorbs at 408 cm⁻¹ in an FTIR spectrum?
A band near 408 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 4 cited sources
Snabbt svar
A band near 408 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.
Möjliga identifieringar av funktionella grupper
| Funktionell grupp | Stödjande fakta | Citerade källor | Högsta förtroende |
|---|---|---|---|
| Methoxy (OCH3) | 2 | 2 | 1,0 |
| Methacrylate | 2 | 2 | 1,0 |
| C-O single bond | 2 | 2 | 1,0 |
| Acetate | 2 | 2 | 1,0 |
| Metal oxygen | 1 | 1 | 1,0 |
| Methyl | 1 | 1 | 1,0 |
| Alkyl C-H | 1 | 1 | 1,0 |
| Ester | 1 | 1 | 1,0 |
| Silicon (Si) | 1 | 1 | 1,0 |
| Siloxane (Si-O-Si) | 1 | 1 | 1,0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1,0 |
Rankingen speglar ackumulerade litteraturbevis, inte en enda auktoritativ regel. Bekräfta alltid mot din provkontext.
Möjliga material
| Material | Stödjande toppar | Överlappande grupper | Citerade källor |
|---|---|---|---|
| PLA | 408, 1650, 1073 | Methacrylate, Acetate, Methoxy (OCH3) | 1 |
| PE | 408, 1414, 1700 | Methacrylate, Acetate, Methoxy (OCH3) | 1 |
| PP | 408, 1700, 1043 | Methacrylate, Acetate, Methoxy (OCH3) | 1 |
Material visas endast när samma litteraturpool stöder detta band och minst en ytterligare karakteristisk topp.
Spektrumlogik
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 408 cm⁻¹ is usually not enough for material identification by itself.
Användning i verkligheten
Denna typ av fråga är vanlig inom polymeridentifiering, screening av okänd plast, felsökning av kvalitetskontroll, verifiering av återvunnet material och litteraturstödd toppidentifieringsgranskning.
Vanliga misstag
- Behandla ett isolerat band som bevis på ett material utan att kontrollera minst en eller två stödjande toppar.
- Ignorerar överlapp: flera funktionella grupper kan bidra nära samma vågtal.
- Hoppa över validering när tillsatser, blandningar, oxidation eller föroreningar kan förvränga spektrat.
Verifieringsråd
När oklarhet kvarstår, validera hypotesen med DSC, GC-MS eller TGA, särskilt för blandningar, nedbrutna prover och fyllda polymerer.
Litteratur bakom dessa identifieringar
-
Silicon-oxygen (Si-O) förtroende 1,0
“α-Fe 295 2O 3 330 O-Si-O deformation vibration 408 Si-O-Si bending vibration”
Wu 等 - 2022 - Comparison of Natural and Dyed Fire Opal DOI: 10.3390/cryst12030322 -
Acetate förtroende 1,0
“vibration showed a band at 408 In contrast to IR spectra, C-O bond ester vibrations in PLA were weak, cm-1 and the Raman bands with maxima at 1043 and 1128 were associated with C-CH vibrations.”
Optical photothermal infrared spectroscopy with simultaneously acquired Raman spectroscopy for two-dimensional microplastic identification DOI: 10.1038/s41598-022-23318-2 -
Acetate förtroende 1,0
“408 cm-1, and C-O-C + C-CH3 vibration assigned to 302-315 cm-1.”
Impact of the Fused Deposition (FDM) Printing Process on Polylactic Acid (PLA) Chemistry and Structure DOI: 10.3390/app7060579 -
Metal oxygen förtroende 1,0
“-1 The spectra of vine black show additional bands at 224, 243 and 290 cm due to -1 symmetric bending of the Fe-O bond, bands at 408, 495, 608 and 659 cm due to symmetric and asymmetric vibrational modes of Fe-O bond [61] and bands at”
Lluveras-Tenorio 等 - 2019 - A multi-analytical characterization of artists' ca DOI: 10.1007/s10973-019-08522-z
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