What absorbs at 2864 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 2864 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 2864 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

• Alkyl C-H confidence 1.0

  “The absorption band at around 2864 and 1656 represent vibrations of the C-H groups and C = O carbonyl groups, respectively.”

  Rupiasih 等 - 2019 - The Current-Voltage Properties of ChAgNP Composit DOI: 10.1088/1757-899X/515/1/012064
• Alkyl C-H confidence 1.0

  “The and CH stretching at 2994 and However, 3 at1723cm-1 spectrum of pure PLA (Figure 2(a)) showed absorption stretching vibration of PCL and CH stretching 2 2864cm-1 C�O bands corresponding to stretching vibration at at were absent.”

  Jeon 等 - 2018 - Improvements in the Rheological Properties, Impact DOI: 10.1155/2018/5316175
• Acetate confidence 1.0

  “symmetric C=H stretching 2864 C=O stretching 1730 [87,94] PCL C-O/C-C stretching”

  Kravanja 和 Finsgar - 2021 - Analytical Techniques for the Characterization of DOI: 10.3390/biomedicines9121936
• Hydroxyl (O-H) confidence 1.0

  “The peaks at 2864 cm-1 and 2936 cm-1 cm-1 cm-1 3470 is the stretching vibration absorption peak of O-H.”

  Application of a Superplasticizer in Scheelite Selective Flotation from Calcite DOI: 10.3390/min12040483
• Alkyl C-H confidence 1.0

  “For IAX, the peaks at 2922 and 2864 cm-1 corresponded to -CH2 and -CH3 stretching vibrations (Zhang et al., 2018;”

  Zou 等 - 2022 - Dispersion of sodium phytate on muscovite and the DOI: 10.37190/ppmp/154951