What absorbs at 1840 cm⁻¹ in an FTIR spectrum?
A band near 1840 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 5 cited sources
Quick answer
A band near 1840 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.
Mogelijke functionele-groeptoewijzingen
| Functionele groep | Ondersteunende feiten | Geciteerde bronnen | Hoogste vertrouwen |
|---|---|---|---|
| Ester | 2 | 2 | 1,0 |
| Methoxy (OCH3) | 1 | 1 | 1,0 |
| C-O single bond | 1 | 1 | 1,0 |
| Methacrylate | 1 | 1 | 1,0 |
| Ketone | 1 | 1 | 1,0 |
| Carboxyl (COOH) | 1 | 1 | 1,0 |
| Carbonyl (C=O) | 1 | 1 | 1,0 |
| Amide | 1 | 1 | 1,0 |
| Acetate | 1 | 1 | 1,0 |
Ranglijst weerspiegelt cumulatief literatuurbewijs, niet één gezaghebbende regel. Bevestig altijd aan de hand van uw monsterecontext.
Possible materials
| Materiaal | Ondersteunende pieken | Overlapping groups | Geciteerde bronnen |
|---|---|---|---|
| Polyester | 1840, 1700, 1250 | Methacrylate, Ester, Methoxy (OCH3) | 1 |
| glycerol | 1840, 1585, 1630 | Methacrylate, C-O single bond, 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 1840 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.
Literatuur achter deze toewijzingen
-
Acetate vertrouwen 1,0
“In the next step, citraconic anhydride was observable by the band at 1840 cm-1 and 1765 cm-1 (C=O stretching of anhydride compounds) and 920 cm-1 (C-O stretching of the C-O-C) [43,44].”
Bio-Based Phosphate-Containing Polyester for Improvement of Fire Reaction in Wooden Particleboard DOI: 10.3390/polym15051093 -
Ester vertrouwen 1,0
“LLM confirmed rule peak-group candidate”
Yang 等 - 2015 - Improved Dissolution Behavior of Aceclofenac Loadi DOI: 10.7317/pk.2015.39.1.6 -
vertrouwen 0,95
“Explicit assignment: 'bridge-bonded CO (CO B) species, which give rise to IR absorption near 1840 cm~1'”
Sun 和 Zhou - 2001 - Surface processes and kinetics of CO2 reduction on DOI: 10.1039/b100938i -
vertrouwen 0,9
“Band in region of coordinated NO”
de Souza Gois 等 - 2019 - A ruthenium nitrosyl cyclam complex with appended DOI: 10.1016/j.poly.2019.114117 -
vertrouwen 0,7
“Text: 'peaks at 1840 after ... multivacancy defects and hydrogen-terminated GeH were identified.'”
Rochat 等 - 2010 - Germanium and Silicon A Comparative Study of Hydr DOI: 10.1149/1.3329611(cid:4)
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