What absorbs at 3624 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 3624 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 fixed 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 3624 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

• Hydroxyl (O-H) confidence 1.0

  “The presence of similar bands at 3624.3, 3620.4, 3627.1, 3624.5, 3626.7 and 3620.7 cm-1 show the [O-H] stretching of the inner hydroxyl group.”

  Unique Halloysite Nanotubes–Polyvinyl Alcohol– Polyvinylpyrrolidone Composite Complemented with Physico–Chemical Characterization DOI: 10.3390/polym9060207
• Hydroxyl (O-H) confidence 1.0

  “For OPT samples exhibited cm(cid:0) 1 strong band at 3624 attributed to the intensity of OH group which indicates the hygroscopic states of OPT.”

  Microencapsulation of ginger-based essential oil (Zingiber cassumunar roxb) with chitosan and oil palm trunk waste fiber prepared by spray-drying method DOI: 10.1016/j.csite.2020.100606
• confidence 1.0

  “3500-500 cm-1, In range of all the three spectra are charcm-1 3390cm-1 Stability and reusability of hybrid composite -3% acterized bybands at 3624 and corresponding 2P90 TiO tostretchingvibration of the hydroxylgroup.The valenceand deformat”

  New composite material based on Kaolinite, cement, TiO2 for efficient removal of phenol by photocatalysis DOI: 10.1007/s11356-021-13150-y
• Carboxyl (COOH) confidence 1.0

  “1400cm-1 cm-1, - bending band of COOH at overlaps with the band of presence of quartz and kaolinite with sharp bands at 3698 carboxylate-COO-groupsandis,thereforenot,indicative.Howeverthe 3653cm-1,and~3620cm-1.ThelatterbandoverlapswiththeO-”

  The nature of interlayering in clays from a podzol (Spodosol) from the Tatra Mountains, Poland DOI: 10.1016/j.geoderma.2010.10.013
• Hydroxyl (O-H) confidence 1.0

  “cm-1 The peak at 3623.8 corresponds to the OH stretching [46] and is present only cm-1 in the virgin membrane, since it was degraded after being used.”

  Barros 等 - 2020 - A three-stage chemical cleaning of ion-exchange me DOI: 10.1016/j.desal.2020.114628
• Metal oxygen confidence 1.0

  “The absorption peak at 3624.03 stretching Al-O-H band) is assigned to the structure.”

  Synthesis and characterization of comb-shaped copolymer as a filtration reducer and comparison with counterparts DOI: 10.1039/c7ra13255g
• Hydroxyl (O-H) confidence 1.0

  “The FTIR spectrum of Mt showed an O-H stretching vibration band of the structural O-H group at 3624 cm-1 and the H-O-H stretching vibration band of the interlayer water in Mt at 3410 cm-1.”

  Fabrication of Colored Polymeric Membrane Using Clay-Based Nano Pigments of Safranin O (SO) Dye DOI: 10.3390/membranes13070619
• Hydroxyl (O-H) confidence 1.0

  “A sharp peak at wavenumber of around 3600 cm-1, related to the absorption band of the O-H stretching vibration that binds to nickel, 3624 cm-1, attributed to the absorption was also observed.”

  Saepudin 等 - 2021 - Nickel Hydroxide Nanoparticles for Application in DOI: 10.18494/SAM.2021.3214