What absorbs at 2948 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 2948 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.

Возможные назначения функциональных групп

Ранжирование отражает накопленные литературные данные, а не единственное авторитетное правило. Всегда проверяйте в контексте вашего образца.

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 2948 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.

Литература, лежащая в основе этих назначений

• Alkyl C-H достоверность 1,0

  “The two cm-1 bands at 2991 and 2948 can be attributed to the C-H bond stretching vibrations of the -CH and 3 bands at 2991 and 2948 cm-1 can be attributed to the C-H bond stretching vibrations of the -CH3 and -CH 2groups, respectively.”

  Awad 等 - 2020 - Experimental Investigation of Methyl Methacrylate DOI: 10.3390/ma13245793
• Alkyl C-H достоверность 1,0

  “cm-1, At 2948 one can see stretches on the main aliphatic chain of the alkanes and alkyl groups (C-H) with moderately strong absorption intensities, which show no change in the function of the cm-1 number of cryogelification cycles.”

  Coria-Hernandez 等 - 2018 - Thermal, Structural, and Rheological Characterizat DOI: 10.3390/polym10040359
• Alkyl C-H достоверность 1,0

  “2, the broad peak near 3396 was the stretching vibration peak of the cm-1 N-H group participating in the hydrogen-bonding carbamate, while the peak at 2948 was the methylene stretching vibration.”

  Jin 等 - 2021 - Preparation of Microspheres and Microfiber Membran DOI: 10.1002/app.39967
• достоверность 1,0

  “Amide A: peptide, protein N-H stretching 3053 Amide B: peptide, protein N-H stretching 2948”

  Metabolic Profile Characterization of Different Thyroid Nodules Using FTIR Spectroscopy: A Review DOI: 10.3390/metabo12010053
• Alkyl C-H достоверность 1,0

  “C-Hstretching cm-1, cm-1, at 2948 and 2897 C-H deformation of secondary alcohol at 1333 and 1239 C-O stretching cm-1, cm-1”

  Zhuang 等 - 2020 - Observation of Potential Contaminants in Processed DOI: 10.3390/app10124345