What absorbs at 652 cm⁻¹ in an FTIR spectrum?
A band near 652 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 652 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 |
|---|---|---|---|
| Alkyl C-H | 2 | 2 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| Protein alpha helix | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Silicon hydride | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.
Possible materials
| Material | Supporting peaks | Overlapping groups | Cited sources |
|---|---|---|---|
| Chitosan | 652, 1650, 1655 | Alkyl C-H | 1 |
| silver nanoparticles | 652, 1636, 1631 | Alkyl C-H | 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 652 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
-
Silicon hydride confidence 1.0
“cm-1correspondings 1043 1175 The band at 652 to Si-H wagging or cmrocking mode matched with previous research groups [27]while the strong band at 780-800 1corresponds to Si-C stretching mode [27,28].”
Swain - 2022 - Process Dependent Strain Behaviour, Fractal Analys DOI: 10.21203/rs.3.rs-374154/v1 -
Amide confidence 1.0
“(2) disappears in had new absorption peaks at 1,640 cm-1 1,412cm-1, 1,556 and corresponding to amide I peak (1,652 cm-1),”
Khodaei 等 - 2018 - Covalent Immobilization of Protein A on Chitosan a DOI: 10.1093/chromsci/bmy070 -
Alkyl C-H confidence 1.0
“LLM confirmed rule peak-group candidate”
Evaluation of therapeutic potential of the silver/silver chloride nanoparticles synthesized with the aqueous leaf extract of Rumex acetosa DOI: 10.1038/s41598-017-11853-2 -
Protein alpha helix confidence 1.0
“(2006), the o m 1,652cm-1 α-helical peak at was found to correspond to”
Lilienthal 等 - 2015 - Changes in the protein secondary structure of hen' DOI: 10.3382/ps/peu051 -
Silicon (Si) confidence 1.0
“The peaks at 652, 837, and 955 which were associated with the Si-O stretching”
Madadi 和 Wei - 2022 - Characterization of Calcium Silicate Hydrate Gels DOI: 10.3390/gels8020075 -
Alkyl C-H confidence 1.0
“The peaks between 652corresponds to C-H stretching vibrations specific cm-1 685 corresponds to the vibration absorption of to CH and CH from lipids, metoxy derivatives,”
Spectroscopic investigation and chemical fingerprint of Datura innoxia dry biomass DOI: 10.5802/crchim.169
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