What absorbs at 2941 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 2941 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 2941 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

  “In free 3BTC, the O-H vibration, FITR H 2941 et al.”

  Lestari 等 - 2022 - Zirconium(IV)-BTC-Based MOF Modified with Nickel a DOI: 10.17576/jsm-2022-5109-16
• Alkyl C-H confidence 1.0

  “stretching vibrations of -CH2”

  Rupiasih 等 - 2018 - Study on Transport Properties of Chitosan Membrane DOI: 10.5614/j.math.fund.sci.2018.50.2.6
• Alkyl C-H confidence 1.0

  “stretch of alkanes was indicated by a peak shape with different particle sizes whereas thiolated 2940.7691cm-1.”

  Zaman 等 - 2021 - Synthesis of Thiol-Modified Hemicellulose, Its Bio DOI: 10.3389/fphar.2021.550020
• Alkyl C-H confidence 1.0

  “LLM confirmed rule peak-group candidate”

  Modifying Cellulose Acetate Mixed-Matrix Membranes for Improved Oil–Water Separation: Comparison between Sodium and Organo-Montmorillonite as Particle Additives DOI: 10.3390/membranes11020080
• Carboxyl (COOH) confidence 1.0

  “Strong stretching Garlic and Ginger added ZrNnanoparticle O-H 3274 Carboxylic acid Strong stretching C-H 2941 Alkane Medium stretching”

  Chowdhury 等 - 2023 - Green synthesis and characterization of zirconium DOI: 10.1016/j.heliyon.2022.e12711
• Carbonyl (C=O) confidence 1.0

  “Peaks ranging from 1670 to cm-1 addition, the peaks at 1971 cm-1, 2177 cm-1, and 2941 cm-1 are similar to the ones observed for the 1780 could be attributed to the stretching vibration of carbonyl (C=O) group of the CNTs [15].”

  Performance of Carbon Nanotube/Polysulfone (CNT/Psf) Composite Membranes during Oil–Water Mixture Separation: Effect of CNT Dispersion Method DOI: 10.3390/membranes7010014
• Alkyl C-H confidence 1.0

  “Theabsorptionbands The absorption bands at 2941 and 2843 cm-1 characteristic for the C-H bond in -CH3 and -CH2 groups cm-1 at 2941 and 2843 characteristic for the C-H bond in -CH and -CH groups occur at K_M10P, 3”

  Bacterial Nanocellulose from Side-Streams of Kombucha Beverages Production: Preparation and Physical-Chemical Properties DOI: 10.3390/polym9080374
• Alkyl C-H confidence 1.0

  “LLM confirmed rule peak-group candidate”

  Kamboj 和 Verma - 2019 - Palmitic Acid-Pluronic F127-Palmitic Acid Pentablo DOI: 10.4274/tjps.galenos.2018.20082