What absorbs at 1409 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 1409 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 1409 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

• Acetate confidence 1.0

  “cm-1, the monomers of both gums, as well as the bands present at 1627 and 1409 which are related to The band on the scaffold spectrum at 1149 cm-1 is derived from the C-O type bonds present in the monomers of both gums, as well as the bands”

  Development of Composite Scaffolds Based on Cerium Doped-Hydroxyapatite and Natural Gums—Biological and Mechanical Properties DOI: 10.3390/ma12152389
• Carboxyl (COOH) confidence 1.0

  “Explicitly stated as -OH of -COOH group bending.”

  Studies on the photodegradation of polarized UV-exposed PMDA-ODA polyimide films DOI: 10.1002/app.11315
• Alkyl C-H confidence 1.0

  “LLM confirmed rule peak-group candidate”

  Kim 和 Kang - 2012 - Fabrication of a Crack-Free Large Area Photonic Cr DOI: 10.1021/cg3005147
• Alkyl C-H confidence 1.0

  “cm(cid:0) 1 The new peaks at 1409 and 970 in VTES modified ZnO nanoZn-O-Si particles can be attributed to CH2 bending and stretching vi2.2.2.6.”

  Surface modification of zinc oxide nanoparticles by vinyltriethoxy silane (VTES) DOI: 10.1016/j.inoche.2020.108347
• confidence 1.0

  “In general, the peaks ranging from 1400~1600 represent the O-C-O stretching bond [27] cm-1 and then the peak at 1409 and 1585 are the symmetrical and asymmetrical stretching C-O of the carboxylate group from alginate [28].”

  Kim 等 - 2019 - The Application of Alginate Coated Iron Hydroxide DOI: 10.3390/app9183835
• S s confidence 1.0

  “Peak A (1409 bands are CH while modes 20 and 21 are the in-phase and out-of-phase CH s s”

  CH Mode Mixing Determines the Band Shape of the Carboxylate Symmetric Stretch in Apo-EDTA, Ca2+–EDTA, and Mg2+–EDTA DOI: 10.1021/acs.jpca.1c03061
• N eq o confidence 1.0

  “5) showed six peaks which indicate the pres1409.02 is assigned to N=O bending nitro groups.”

  Ragavendran 和 Natarajan - 2015 - Insecticidal potency of Aspergillus terreus agains DOI: 10.1007/s11356-015-4961-1
• Acetate confidence 1.0

  “attached to the aromatic graphene network at 1409 the C-O (hydroxyl) stretching at 1601 cm-1 cm-1 the C-O (epoxy) stretching at 1040 and the C-O (phenolic) stretching at 1213 [18,30].”

  Preparation of Electrospun Nanocomposite Nanofibers of Polyaniline/Poly(methyl methacrylate) with Amino-Functionalized Graphene DOI: 10.3390/polym9090453