What absorbs at 488 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 488 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.

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 488 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

  “peak at ~488 due to Zn-O stretching mode.”

  Chakraborty 等 - 2012 - ZnOTi Thin Film Synthesis, Characterization and DOI: 10.1088/1742-6596/390/1/012065
• Hydroxyl (O-H) confidence 1.0

  “The Mn doping has in900 which correspond to strain vibration of O-H group of duced a change of particle shape, from the typical rod-like one 900 which correspond to strain vibration of O-H group of duced a change of particle shape, from the”

  Harsono 等 - 2017 - Paramagnetic Zn(1-x)MnxO (0.00≤x≤0.06) Nanopar DOI: 10.4313/TEEM.2017.18.1.46
• confidence 1.0

  “Vibrations(cm-1) Assignment 488 Si O SirockingvibrationinLOmode 522 LowerfrequencySi Ovibration”

  Jana 等 - 2008 - Non-hydrolytic sol-gel synthesis of epoxysilane-ba DOI: 10.1016/j.matchemphys.2008.06.070
• Carboxyl (COOH) confidence 1.0

  “The equivalent carboxyl group peaks in 488 (1:100) U.K.) in 1% BSA in PBS, was cm-1, respectively18 pure Tar are observed at 1550 and 1740 consequently added to the samples and incubated for 1 h at room confirms temperature followed by anot”

  Chiral Tartaric Acid Improves Fracture Toughness of Bioactive Brushite–Collagen Bone Cements DOI: 10.1021/acsabm.0c00555
• Phosphate (PO4) confidence 1.0

  “The strong adsorption band at around 1125 cm-1 was ascribed to an asymmetric P-O-Al stretching vibration, and the one at 488 cm-1 was assigned to symmetrical P-O-Al deformation vibration [38,39];”

  Efficient and Stable O-Methylation of Catechol with Dimethyl Carbonate over Aluminophosphate Catalysts DOI: 10.3390/catal13010150
• confidence 0.9

  “Explicit assignment in text.”

  Magnetic Properties of MFeCrO4 (M = Co/Ni) Prepared by Solution Combustion Method DOI: 10.1007/s10948-019-5080-x
• confidence 0.8

  “Assigned to ν(Sn-O) in region 488-495”

  Tributyltin(IV) Butyrate: A Novel Epigenetic Modifier with ER Stress- and Apoptosis-Inducing Properties in Colon Cancer Cells DOI: 10.3390/molecules26165010