What absorbs at 1991 cm⁻¹ in an FTIR spectrum?
A band near 1991 cm⁻¹ can point to several functional groups. Below are the most likely assignments, ranked by how much published evidence supports each — every one traceable to literature (DOI) and cross-validated against our 130,000+ reference spectra and knowledge graph.
Backed by 6 cited sources
Quick answer
A band near 1991 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
| 官能团 | 支持性事实 | 引用来源 | 最高置信度 |
|---|---|---|---|
| Aromatic ring | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
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。
Possible materials
| 材料 | 支持峰 | Overlapping groups | 引用来源 |
|---|---|---|---|
| lignin | 1991, 1035, 1510 | Methacrylate, Aromatic ring, Methoxy (OCH3) | 2 |
| wood | 1991, 1740, 1730 | Methacrylate, Methoxy (OCH3), Aromatic ring | 2 |
| cellulose | 1991, 1735, 1650 | Methacrylate, Methoxy (OCH3) | 1 |
| hemicellulose | 1991, 1730, 897 | Methacrylate, Methoxy (OCH3), Carbonyl (C=O) | 1 |
| TiO2 | 1991, 1700, 1093 | Methacrylate, Methoxy (OCH3) | 1 |
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 1991 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
“The intensity of this peak is inversely Caesalpiniaceae, Annonaceae, Bombacaceae, Dipterocarpaceae, proportional to CH stretching vibration (Rochdi and Landias, 1991;”
Mathews 等 - 2018 - Characterization of Panandhro Lignite Deposits (Ka DOI: 10.1007/s12594-018-851-8 -
Aromatic ring 置信度 1.0
“Pandey (1999) CsO 3 1596 Aromatic skeletal vibration plus stretch Faix (1991), Faix et al.”
Rana 等 - 2008 - FTIR spectroscopy in combination with principal co DOI: 10.1515/HF.2008.104 -
Aromatic ring 置信度 1.0
“cm1, For hemicelluloses and lignin, the characteristic peaks at 1735 1510 and 810 belonged to C = O stretching vibrations in the O = C-OH group of the glucuronic acid unit in xylan (Åkerholm and Salmén, 2001), to the aromatic skeletal vibra”
Wang 等 - 2022 - Molecular-level characterization of changes in the DOI: 10.21203/rs.3.rs-882939/v1 -
置信度 1.0
“2,921cm-1 groups,whilethe2,877cm-1 acetylene, whose formation is accompanied by the complete isduetoaliphatic-CH 3 erosion of the OH groups features with maxima at 3,716 and (Colthup et al., band may be due to -CH of alkanes, respectively c”
Carbon Domains on MoS2/TiO2 System via Catalytic Acetylene Oligomerization: Synthesis, Structure, and Surface Properties DOI: 10.3389/fchem.2017.00091 -
Acetate 置信度 1.0
“Hemicellulose 1245 C-O stretch (Faix, 1991) Hemicellulose D 1735-1740 C=O stretching in glucuronic acid (xylan) (Marchessault, 1962;”
Dinant 等 - 2019 - Synchrotron FTIR and Raman spectroscopy provide un DOI: 10.1093/jxb/ery396 -
Carbonyl (C=O) 置信度 1.0
“In addition, 1601 is also associated with the C=O asymmetric stretching vibration (Faix 1991).”
Zhu 等 - 2022 - The spatial orientation and interaction of cell wa DOI: 10.21203/rs.3.rs-1076632/v1
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