What absorbs at 450 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 450 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.

Possible functional-group assignments

Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.

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 450 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.

Literature behind these assignments

• confidence 1.0

  “The cm-1 567cm-1 absorption bands ~ 449.86 and ~ are associated with the stretching vibration of cm-1 Fe-O and FeO octahedral rotation.”

  Evolution of structure and improvement in dielectric properties of praseodymium substituted YFeO3 nanomaterials synthesized via a sol-gel auto-combustion method DOI: 10.1016/j.ceramint.2020.11.005
• Carbohydrate confidence 1.0

  “We note that Shrimp ShP is more between 390 and 530 with maximum peak of 450 due to polycrystallinethanallourchitosansamplesbecauseitsbuildslowlywiththe saccharides decomposition.”

  A comparison of chitosan properties after extraction from shrimp shells by diluted and concentrated acids DOI: 10.1016/j.heliyon.2020.e03486
• confidence 1.0

  “FT-IR spectra Nanoparticles cm-1 ∼450 depicts a strong band at which corresponds to the bending vibration of Ni-O bond.”

  Synthesis of nickel oxide nanoparticles using pulsed laser ablation in liquids and their optical characterization DOI: 10.1016/j.apsusc.2012.03.147
• Silicon (Si) confidence 1.0

  “A weak absorption peak at 450 cm-1 corresponds to the Si-N stretching while a N-H bending peak is also observed at 1180 cm-1 [20].”

  Deposition of Silicon Nitride Films using Chemical Vapor deposition for Photovoltaic Applications DOI: 10.1016/j.rinp.2016.11.029
• confidence 1.0

  “FTIR studies reveal the presence of multiple peaks in the 1000-1600 cm-1 cm-1 region due to Na-O, K-O vibrations and at ~450 and 584 due to Fe-O and Co-O bonds.”

  Kirana 等 - 2018 - Synthesis and Characterization of Sodium Potassium DOI: 10.1080/0371750X.2018.1465359
• Silicon (Si) confidence 1.0

  “The peaks centred at 450 and 964 are attributed to Si-N stretching due to the silicon nitride.”

  Optical and photoelectrochemical properties of nitrogen-doped a-SiC thin films deposited by reactive DOI: 10.1080/2374068X.2021.1890420
• N-O bond confidence 1.0

  “system27 at 406/395 and 369/362 No other isotope-difference peaks in 1, whereas in the corresponding unbridged is at 450 cm-1.”

  Pinakoulaki 等 - 2003 - The active site structure of heme a(3)(3+)-C N-Cu- DOI: 10.1021/jp034326g
• Metal oxygen confidence 1.0

  “The peak emerging at cm-1 450 is attributed to Y-O vibrational mode [9].”

  Synthesis and luminescence properties of europium-codoped and dysorium-doped YVO4 nanophosphor for potential applications DOI: 10.1007/s00339-019-2990-1