What absorbs at 3680 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 3680 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 3680 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

• Hydroxyl (O-H) 信頼度 1.0

  “The double peaks at 3680 cm-1 and 3633 cm-1 were observed due to the stretching vibration of the hydroxyl group at the surface of HNTs.”

  Synthesis and Optimization of Superhydrophilic-Superoleophobic Chitosan–Silica/HNT Nanocomposite Coating for Oil–Water Separation Using Response Surface Methodology DOI: 10.3390/nano12203673
• 信頼度 1.0

  “The group of peaks from 3680 cm-1 to 3482 cm-1 intense spectral features at 938 and 3680 cm-1 correspond to the position of peaks that arise from OHstretching modes, where OHgroups are bound to Mg (serpentine and stitchtite) or Cr (stitchti”

  Melchiorre 等 - 2020 - Insights on Structure and Threshold Detection Limi DOI: 10.3390/min10030215
• Hydroxyl (O-H) 信頼度 1.0

  “spectra with similar features in this region, in addition to a free Figure 2c shows the probability of a water molecule forming cm-1.22,25,95 cm-1 ∼3680 The 3200 peak has been OH stretch at a particular number of hydrogen bonds within the d”

  Moussa 等 - 2009 - Experimental and Theoretical Characterization of A DOI: 10.1021/jp808710n
• Hydroxyl (O-H) 信頼度 1.0

  “The vibrational bands at between between 3680 cm-1 and 3120 cm-1 are due to O-H and N-H stretching and can be attributed to cm-1 cm-1 between 3680 cm-1 and 3120 cm-1 are due to O-H and N-H stretching and can be attributed to 3680 and 3120 a”

  Self-Healable Supramolecular Vanadium Pentoxide Reinforced Polydimethylsiloxane-Graft- Polyurethane Composites DOI: 10.3390/polym11010041
• Hydroxyl (O-H) 信頼度 1.0

  “CO stretching asym CaCO3 cm-1, 1050-1015 SO stretching Ca(SO4)·2H2O An intense band, between 3680 and 3000 is related to the OH stretchings of celcm-1 870-880 CO stretching asym CaCO3 lulose [46] and absorbed water, while the bending of thi”

  Water-Based Aerosol for Book Deacidification: Experimental Apparatus and Theoretical Interpretation of Results DOI: 10.3390/molecules26144249
• Hydroxyl (O-H) 信頼度 1.0

  “The band of isolated OH groups at 3772 disappeared nearly completely, whereas the intensity of the cm1 hydroxyl stretch vibration band at 3680 decreased”

  Adsorption and Reaction of CO on (Pd–)Al2O3 and (Pd–)ZrO2: Vibrational Spectroscopy of Carbonate Formation DOI: 10.1007/s11244-017-0852-7
• Hydroxyl (O-H) 信頼度 1.0

  “The results are presented in Table 2 that spectra of feedstock mainly possess peaks at around 3680cm-1 cm-1 O-H lignin, 1 3000 are assigned to stretching from peaks around 3000-2800 represent the C-H stretching 3 D cm-1”

  Jaruwat 等 - 2018 - Effects of Hydrothermal Temperature and Time of Hy DOI: 10.1063/1.5053192
• Hydroxyl (O-H) 信頼度 1.0

  “This spectrum Scientific), low-temperature chamber (Harrick evacuated to the lowest (3725cm-1, exhibits IR bands of surface hydroxyls of anatase (ca.<10-3mbar) stable pressure and kept under dynamic vacuum for 3632cm-1) (3680cm-1, 3414cm-1)”

  Litke 等 - 2019 - Interfacial charge transfer in Pt-loaded TiO2 P25 DOI: 10.1016/j.jphotochem.2018.10.023