What absorbs at 662 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 662 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 authoritative rule. Always confirm against your sample context.

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 662 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

• Metal oxygen confidence 1.0

  “FTIR spectrum cm(cid:1)1 of SnQ shows band at 662 and a strong one at 564 which are Sn-O Sn-OH due to stretching and respectively [39,40].”

  Shajira 等 - 2015 - Sunlight assisted photodegradation by tin oxide qu DOI: 10.1016/j.jpcs.2015.09.003
• Amide confidence 1.0

  “(ii) the band at 662 assigned to the combination of stability.38 chemical behavior and In particular, NaBF was used ν(C-N) and δ ring modes;”

  Dani 等 - 2015 - Design of high surface area poly(ionic liquid)s to DOI: 10.1039/c5ta00272a
• C-O single bond confidence 1.0

  “The band approximately at 662cm-1 mately at referred to the C-OH of plane bending mode.”

  Investigate the role of fungal communities associated with a historical manuscript from the 17th century in biodegradation DOI: 10.1038/s41529-022-00296-4
• Aromatic ring confidence 1.0

  “The band around 662 cm-1 may be assigned to the -CHbonding of aromatic groups [32].”

  Impact and Tensile Properties of Polyester Nanocomposites Reinforced with Conifer Fiber Cellulose Nanocrystal:A Previous Study Extension DOI: 10.3390/polym13111878
• C-O single bond confidence 1.0

  “The little peaks at approximately 662 C-OH bending (Fan et al.”

  Chemical functional groups of extractives, cellulose and lignin extracted from native Leucaena leucocephala bark DOI: 10.1007/s00226-020-01258-2
• Acetate confidence 1.0

  “sorption, the weak peaks at wavenumber 662 cm-1 (the expected bond is O 1CO 2), after CO 2 cm-1 cm-1 C-O+C···O), strong peaks at wavenumber 1007 (the expected bond is 1402 (the and 840 cm-1 (the expected bond is CO 3) are attributed to carb”

  CO2 Sorption and Regeneration Properties of K2CO3/Al2O3-Based Sorbent at High Pressure and Moderate Temperature DOI: 10.3390/app12062989
• Phosphate (PO4) confidence 1.0

  “In the spectrum of BG: P-O wagging is centered at 456 and P-O scissoring is centered at 662 cm-1 cm-1.”

  Molecular and biological activities of metal oxide-modified bioactive glass DOI: 10.1038/s41598-023-37017-z
• confidence 0.9

  “Explicit assignment: 'and to maghemite (662 cm-1)'”

  Desferrioxamine B: Investigating the Efficacy of Hydrogels and Ethanol Gels for Removing Akaganeite and Maghemite from Dry Wooden Substrates DOI: 10.3390/f14020247