What absorbs at 408 cm⁻¹ in an FTIR spectrum?

Quick answer

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.

可能性のある官能基アサイン

ランキングは蓄積された文献証拠を反映しており、単一の権威あるルールではありません。常にサンプルのコンテキストと照合して確認してください。

Possible materials

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 408 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.

これらのアサインの根拠となる文献

• Silicon-oxygen (Si-O) 信頼度 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 信頼度 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 信頼度 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 信頼度 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