What absorbs at 2355 cm⁻¹ in an FTIR spectrum?
A band near 2355 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 2355 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.
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Carbon dioxide | 3 | 3 | 1.0 |
| Siloxane (Si-O-Si) | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1.0 |
| Metal oxygen | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Possible materials
| Material | Supporting peaks | Overlapping groups | Cited sources |
|---|---|---|---|
| oil shale | 2355, 1625, 1053 | Silicon-oxygen (Si-O) | 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 2355 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.
Literature behind these assignments
-
Alkyl C-H confidence 1.0
“cm-1 The band at 2355 was attributed to the presence of C-H stretching vibrations, which cm-1 were indicative of the presence of methyl groups.”
Antimicrobial Activity of Chemically and Biologically Treated Chitosan Prepared from Black Soldier Fly (Hermetia illucens) Pupal Shell Waste DOI: 10.3390/microorganisms9122417 -
Carbon dioxide confidence 1.0
“(νNH 3) and 1626, 966 (δNH 3), CO (characteristic 2 cm-1 The differences that may arise between them are probably absorption bands at 2355 and 2311 ( νCO 2) and cm-1 cm-1 due to the fact that GS curve profile is related to the molar 669 (δ”
Junior Caires 等 - 2017 - Thermoanalytical, Spectroscopic and DFT Studies of DOI: 10.1590/1980-5373-MR-2016-0633 -
Amide confidence 1.0
“The IR spectrum of probiotics-loaded whey nanoparticles demonstrated a significant signal at 2355 cm-1 corresponding to the amide O=C=O stretch vibration.”
Effect of protein-based nanoencapsulation on viability of probiotic bacteria under hostile condition DOI: 10.1080/10942912.2023.2228514 -
Hydroxyl (O-H) confidence 1.0
“The bands located around ~3432, ~3624, and ~3696 cm-1 were characteristic of OH group vibration elongation whereas the band ~2355 could Table 4.”
Structural Study of Nano-Clay and Its Effectiveness in Radiation Protection against X-rays DOI: 10.3390/nano12142332 -
Carbon dioxide confidence 0.9
“Text states 'peak at the wavenumber of 2355 indicates that CO2 is a main component'.”
Xie Fang-Fang 等 - 2010 - STUDY ON THERMAL CONVERSION OF HUADIAN OIL SHALE U DOI: 10.3176/oil.2010.4.04
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