What absorbs at 646 cm⁻¹ in an FTIR spectrum?
A band near 646 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 646 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 |
|---|---|---|---|
| Metal oxygen | 3 | 3 | 1,0 |
| Borate | 1 | 1 | 1,0 |
| Chlorine | 1 | 1 | 1,0 |
| Hydroxyl (O-H) | 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 |
| N-O bond | 1 | 1 | 1,0 |
| Ring structure | 1 | 1 | 1,0 |
| C#c | 1 | 1 | 0,6 |
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 |
|---|---|---|---|
| quercetin | 646, 1745, 1612 | Hydroxyl (O-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 646 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
-
Ring structure vertrouwen 1,0
“IR and Raman bands observed at 646, 1115, 1587 and 646, cm-1 1110, 1270 is due to the ring bending or stretching and stretching vibrations of C-NO and C-O”
Dalal 等 - 2015 - Structural, electrical, ferroelectric and mechanic DOI: 10.1039/C5RA10501C. -
Hydroxyl (O-H) vertrouwen 1,0
“Acorrdcm-1 that were assigned to O-H located at 3369 and 655 literatures,12(cid:4)16 cm-1 the peak of 646 was attributed ing to”
Zhang 等 - 2019 - Synthesis of TiB2 Powders with Hexagonal Morpholog DOI: 10.1166/jnn.2019.16750 -
vertrouwen 1,0
“cm-1 cm-1 parameter in this study, we attempted to estimate those 768 (C-Cl stretch = alkyl halides) and 646 (- C:C-H: phytochemicals quantitatively in MEAIL.”
Identification of food preservative, stress relief compounds by GC–MS and HR-LC/Q-TOF/MS; evaluation of antioxidant activity of Acalypha indica leaves methanolic extract (in vitro) and polyphenolic fraction (in vivo) DOI: 10.1007/s13197-017-2590-z) -
vertrouwen 1,0
“The presence of other bands at 646 and 532 are attributed to stretching vibration ν (Zn-O), this confirm the formation of metal complex [35].”
Refat 等 - 2021 - QuercetinZinc complex and stem cells A new drug DOI: 10.1371/journal.pone.0246265 -
Borate vertrouwen 1,0
“grinding and mixing processes that may affect the borate peak intensity slightly, for example the cm-1 sharp peak at 646 for the physical mixture sample with 0.25 wt.% B 2O may indicate longer sharp peak at 646 cm-1 for the physical mixture”
Development of FTIR Spectroscopy Methodology for Characterization of Boron Species in FCC Catalysts DOI: 10.3390/catal10111327 -
Metal oxygen vertrouwen 0,95
“Text: 'coordinated Al-O was indicated by bands at 747, 646, and 486'”
Retnoningtyas 等 - 2022 - Synthesis and Characterization of Methionine-Funct DOI: 10.33263/BRIAC125.58455859
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