What absorbs at 3651 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 3651 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.

Iespējamie funkcionālo grupu piešķīrumi

Rangs atspoguļo uzkrātos literatūras pierādījumus, nevis vienu autoritatīvu noteikumu. Vienmēr apstipriniet atbilstoši parauga kontekstam.

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 3651 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.

Literatūra aiz šiem piešķīrumiem

• Water (H2O) pārliecība 1,0

  “analyzed by a deconvolution procedure, and the area of a cm-1) specific peak (at 3651 was directly correlated to the amount of water inside the sample.”

  A spectroscopic approach to assess transport properties of water vapor in PLA DOI: 10.1016/j.polymertesting.2015.03.015
• Hydroxyl (O-H) pārliecība 1,0

  “γANPs-CTAB When we compare the FTIR spectra of before and after BPA adsorption (Figure 14a,b), it is observed that the intensities of the -OH stretching mode seen at 3651, cm-1 3643, and 3480 decrease after BPA adsorption.”

  Low-Cost Synthesis of Alumina Nanoparticles and Their Usage for Bisphenol-A Removal from Aqueous Solutions DOI: 10.3390/pr9101709
• Hydroxyl (O-H) pārliecība 1,0

  “hydroxyl groups Al-O-H stretching of inner surface 3651 3651 3651 3651 3651 3651 3651 3651 3651 3651 hydroxyl groups Al-O-H stretching of inner hydroxyl 3619 3619 3619 3619 3619 3619 3619 3619 3619 3621”

  Oyebanjo 等 - 2018 - Mineral Constituents and Kaolinite Crystallinity o DOI: 10.1515/geo-2018-0012
• Hydroxyl (O-H) pārliecība 0,9

  “Explicit assignment for kaolinite OH stretching.”

  Weng 等 - 2020 - Black carbon enriches short-range-order ferrihydri DOI: 10.1016/j.scitotenv.2020.138195
• pārliecība 0,9

  “Explicit assignment in text”

  Mineralogy and geochemistry of clay fractions in soils developed from different parent rocks in Limpopo Province, South Africa DOI: 10.1016/j.heliyon.2021.e07664
• Hydroxyl (O-H) pārliecība 0,9

  “Explicitly assigned to OH stretching region, compared to water monomer.”

  Vibrational investigations of CO2-H2O, CO2-(H2O)2, and (CO2)2-H2O complexes isolated in solid neon DOI: 10.1063/1.4936913
• Hydroxyl (O-H) pārliecība 0,8

  “Assigned to stretching vibration of hydroxyl groups.”

  Multi-Method Analysis of Painting Materials in Murals of the North Mosque (Linqing, China) DOI: 10.3390/coatings13071298