What absorbs at 3698 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 3698 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.

Möjliga identifieringar av funktionella grupper

Rankingen speglar ackumulerade litteraturbevis, inte en enda auktoritativ regel. Bekräfta alltid mot din provkontext.

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 3698 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.

Litteratur bakom dessa identifieringar

• förtroende 1,0

  “cm-1 OHintense peak around 3698 is attributed to the and MgO nanoparticles prepared SEM image of Mg(OH) antisymmetric stretching vibration in the crystal structure 2 using different solvents are shown in Fig.”

  Mageshwari 和 Sathyamoorthy - 2012 - Studies on Photocatalytic Performance of MgO Nanop DOI: 10.1007/s12666-011-0106-5
• förtroende 1,0

  “cm-1 Finally, the bands at ~3698 and 3620 (bands A and C, respectively) are due to AlAlOH stretching vibrations of kaolinite (Balan et al.”

  Schingaro 等 - 2021 - New insights into the crystal chemistry of sauconi DOI: 10.2138/am-2020-7460.
• Hydroxyl (O-H) förtroende 1,0

  “Only three OH stretching vibrations were observed at 3698, 3652, and 3621 301 in ADE and the adjacent soil, pointing to the poorly crystalline nature of kaolinite (Fig.”

  Weng 等 - 2020 - Black carbon enriches short-range-order ferrihydri DOI: 10.1016/j.scitotenv.2020.138195
• Hydroxyl (O-H) förtroende 1,0

  “In the 1), FTIR spectrum of the halloysite clay mineral sample (spectrum the peaks at 3698 and cm-1 3623 were due to the stretching vibrations of the OH groups of the Al-OH.”

  Enhancing the Thermal Stability of Ionogels: Synthesis and Properties of Triple Ionic Liquid/Halloysite/MCC Ionogels DOI: 10.3390/molecules26206198
• Hydroxyl (O-H) förtroende 1,0

  “cm-1), cm-1 cm-1 region (4000~1330 the spectral bands at 3698 and 3448 were related to did not only delay the combustion of the asphalt binder, but it also reduced the combusthe OH stretching vibrations of brucite and water in various state”

  Thermal Degradation Characteristics of Styrene-Butadiene-Styrene Copolymer Asphalt Binder Filled with an Inorganic Flame-Retarding Agent DOI: 10.3390/polym14183761
• Hydroxyl (O-H) förtroende 1,0

  “d final pressure step to 1 mbar, the bands at 3698 and 3571 and 3200 The band assigned to the vibrations OH cm(cid:1)1 cm(cid:1)1, cm(cid:1)1.”

  Muller 等 - 2004 - Interactions of water and methanol with MeAPO-5. F DOI: 10.1016/j.micromeso.2003.12.025
• förtroende 1,0

  “The absorption bands at 3698 and 550 corresponding to Mg-OH cm-1 stretching vibrations revealed the existence of an Mg(OH) film.”

  Wang 等 - 2017 - In Vitro Degradation of PureMagnesium-The Effects DOI: 10.3390/ma10070725