What absorbs at 3494 cm⁻¹ in an FTIR spectrum?
A band near 3494 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 3 cited sources
Quick answer
A band near 3494 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 |
|---|---|---|---|
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
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 3494 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
-
Hydroxyl (O-H) confidence 1.0
“Citricacidshows cm-1 cm-1, cm-1 characteristic peaks at 3494 for O-H stretching vibrations, 1751 and 1704 C=O stretching for COOH groups.”
Development of Co-Amorphous Loratadine–Citric Acid Orodispersible Drug Formulations DOI: 10.3390/pr10122722 -
Silicon-oxygen (Si-O) confidence 1.0
“1610 Likewise, a strong absorption appears at 1002 attributed to Si-O bond stretching at 3494 cm-1, while the bending vibration of the NH group is seen at 1069 cm-1.”
Synthesis and Characterization of a Novel Borazine-Type UV Photo-Induced Polymerization of Ceramic Precursors DOI: 10.3390/molecules21060801 -
Hydroxyl (O-H) confidence 0.8
“Text: 'shoulder at 3494 ... attributed to the stretching mode OH'.”
Capelletti 等 - 1999 - The OH vibrational spectrum in Bi2TeO5 single crys DOI: 10.1080/10420159908245945
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