What absorbs at 2138 cm⁻¹ in an FTIR spectrum?
A band near 2138 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 2138 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.
Iespējamie funkcionālo grupu piešķīrumi
| Funkcionālā grupa | Atbalstošie fakti | Citētie avoti | Augstākā pārliecība |
|---|---|---|---|
| Carbonyl (C=O) | 3 | 3 | 1,0 |
| Carboxyl (COOH) | 2 | 2 | 1,0 |
| Alkyl C-H | 1 | 1 | 1,0 |
| Methacrylate | 1 | 1 | 1,0 |
| Ketone | 1 | 1 | 1,0 |
| Ester | 1 | 1 | 1,0 |
| Amide | 1 | 1 | 1,0 |
| Acetate | 1 | 1 | 1,0 |
| C#c | 1 | 1 | 0,9 |
| Adsorbed carbon monoxide | 1 | 0 | 1,0 |
Rangs atspoguļo uzkrātos literatūras pierādījumus, nevis vienu autoritatīvu noteikumu. Vienmēr apstipriniet atbilstoši parauga kontekstam.
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 2138 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.
Literatūra aiz šiem piešķīrumiem
-
Carbonyl (C=O) pārliecība 1,0
“With time, the bands at 2138, most stable carbonyl band and the bands in the 1774cm(cid:2)1 2249cm(cid:2)1 region are evidently due to carbonyls on reduced chromium spedevelop, the band at de1902, 1794 and”
Influence of dealumination and treatments on the chromium speciation in zeolite CrBEA DOI: 10.1016/j.micromeso.2009.04.038 -
Carbonyl (C=O) pārliecība 1,0
“groups34,53-55 to evacuation, characteristic of CH and CH that as corroborated by the observation of their characteristic di3 2 cm-1 evidence the formation of acyclic hydrocarbon species (Figure carbonyl bands at 2138 and 2095 at low CO cov”
Moussa 等 - 2018 - Nature of Active Nickel Sites and Initiation Mecha DOI: 10.1021/acscatal.7b03970 -
Acetate pārliecība 1,0
“C=O stretch 2138 2343 1722 1700 1590 bend 1494 C-H sym.”
Raunier 等 - 2004 - Tentative identification of urea and formamide in DOI: 10.1051/0004-6361:20034558 -
Carboxyl (COOH) pārliecība 1,0
“OH asymmetrical stretching 2360.30 OH asymmetrical stretching vibration in carboxylic acids vibration in carboxylic acids 2138 -”
Biocatalytic activity of Aspergillus niger xylanase in paper pulp biobleaching DOI: 10.1007/s13205-016-0480-0 -
C#c pārliecība 0,9
“Explicit assignment: 2371.88, 2345.87 and 2138.23 (C≡C)”
Pinto Cotrim 等 - 2016 - Preparation of beta-CyclodextrinLatex Dispersion DOI: 10.7569/JRM.2015.634122 -
pārliecība 0,8
“Text: 'The band at 2138 cm-1 quickly disappear' in context of CO.”
Spezzati 等 - 2017 - Atomically Dispersed Pd-O Species on Ceo(2)(111) a DOI: 10.1021/acscatal.7b02001
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