What absorbs at 3081 cm⁻¹ in an FTIR spectrum?

Quick answer

A band near 3081 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.

可能的官能团归属

排名反映了累积的文献证据，而非单一的权威规则。请始终对照您的样品背景进行确认。

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 3081 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.

这些分配背后的文献

• Alkyl C-H 置信度 1.0

  “LLM confirmed rule peak-group candidate”

  60MeV Ni ion induced modifications in nano-CdS/polystyrene composite films DOI: 10.1016/j.radphyschem.2013.06.022
• Alkyl C-H 置信度 1.0

  “cm-1 ν(CH) 3090-2850 that correspond to alkane modes, with peaks at 3081, 3060, 3028, cm-1.”

  Czylkowska 等 - 2021 - Cytotoxic Activity against A549 Human Lung Cancer DOI: 10.3390/ijms22136692
• Alkyl C-H 置信度 1.0

  “Assignment C-H aromatic ring C-H stretching 3081,3060,3027 ν methyl 2962 (CH 3), C-H asymmetric stretching asym ν methylene (CH 2), C-H asymmetric stretching 2927”

  Filip 等 - 2013 - Investigation of thermal and catalytic degradation DOI: 10.2478/s11532-013-0202-y
• Alkene (C=C) 置信度 1.0

  “At the same time, the peak present in the 3081 in the PPI spectra may be due to cm-1 the presence of =C-H stretching vibration from the alkene functional group.”

  Kasar 和 Ahmaruzzaman - 2022 - Characterization of liquid products obtained from DOI: 10.1038/s41598-022-15371-8
• Alkyl C-H 置信度 1.0

  “In cm-1, cm-1 In the curve of the AllylEHO, new peaks are observed at 3081 1646 and the curve of the AllylEHO, new peaks are observed at 3081 cm-1, 1646 cm-1 and 926 cm-1 cm-1 926 representative of the C-H aliphatic stretch of the character”

  Preparation of Bis[(3-ethyl-3-methoxyoxetane)propyl]diphenylsilane and Investigation of Its Cationic UV-Curing Material Properties DOI: 10.3390/polym13152573
• Aromatic ring 置信度 1.0

  “f cm-1 reaction (Table 2, entry 2) was performed without a solvent, -C-H FTIR: 3081.43 for aromatic stretching, 2983.48 cm-1 without cashew shell extract, and with microwave irradiation -C-H for aliphatic stretching, 1654.06 and 1621.27”

  Manjare 等 - 2023 - Microwave-Assisted Rapid and Green Synthesis of Sc DOI: 10.1021/acsomega.2c05187
• Alkene (C=C) 置信度 1.0

  “stretching wave numbers appear in the range of 3000-3100 Accordingly, in cm-1 the present study, the aromatic =C-H stretching gives bands at 3081 in the”

  Growth, crystal structure, Hirshfeld surface and vibrational properties of a new supramolecular hybrid material: (C4H7N2)2TeBr6 DOI: 10.1007/s00289-021-04053-6
• 置信度 1.0

  “The 1480 cm-1 3 (symmetric NH bend), the 906 cm-1 (NH 3+/CH rock) and the 3081 cm-1 (N-H stretch) 3+ 3”

  Characterization of a New Low Temperature Encapsulation Method with Ethylene-Vinyl Acetate under UV Irradiation for Perovskite Solar Cells DOI: 10.3390/app12105228