What absorbs at 1373 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 1373 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 1373 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

  “Explicit assignment: CH bending of cellulose and hemicellulose”

  Balan 等 - 2021 - Esterification of residual palm oil using solid ac DOI: 10.1016/j.jtice.2012.07.001.
• Alkyl C-H confidence 1.0

  “suggested the active chemical functional groups concentration of H 2 1437cm-1, 1373cm-1 1215cm-1 eCH CeOeC peak at peak at and peak at were susceptible to of>CH 2 3 oxidation.”

  Effect of oxidation processing on the surface properties and floatability of Meizhiyou long-flame coal DOI: 10.1016/j.fuel.2017.08.053
• Carboxyl (COOH) confidence 1.0

  “The peak detected at 1373 was attributed to cm-1 the symmetric carboxyl vibrations.”

  Fabrication of the flexible nanogenerator from BTO nanopowders on graphene coated PMMA substrates by sol-gel method DOI: 10.1016/j.matchemphys.2017.02.002
• Protein confidence 1.0

  “The peak 1373 shows the presence of nitrocompounds from proteins or cm-1 enzymes [28] and that at 1080 can be assigned to -C-Nstretching vibrations [15].”

  Hieu 等 - 2022 - Microorganism-mediated green synthesis of silver n DOI: 10.15251/DJNB.2022.171.359
• Hydroxyl (O-H) confidence 1.0

  “The band at ν ~ 1372.68 cm-1 corresponds to bending vibration of H-O-H bond.”

  Tripathi 等 - 2015 - Effect of Calcination Temperature on Phase Transfo DOI: 10.1063/1.4929229
• Urea confidence 1.0

  “Excitation at cm-1 cm-1 at 1642 (urea band) normalized to 1373 PPO band”

  Fluorescence and IR Characterization of Cure in Polyurea, Polyurethane, and PolyurethaneUrea DOI: 10.1021/ma0113172
• Hydrogen bond confidence 1.0

  “Spectral features of the ring are observed at 1608 The bands observed at 1373, 1243 and to the stretching vibration of the intramolecular hydrogen bond of the amino group of amide A, while cm-1 1036 are attributed to the characteristic vibr”

  Preparation and Physicochemical Characterization of Softgels Cross-Linked with Cactus Mucilage Extracted from Cladodes of Opuntia Ficus-Indica DOI: 10.3390/molecules24142531
• Methyl confidence 1.0

  “Explicitly assigned to -CH3.”

  Biowaxes from Palm Oil as Promising Candidates for Cosmetic Matrices and Pharmaceuticals for Human Use DOI: 10.3390/ma16124402