What absorbs at 3347 cm⁻¹ in an FTIR spectrum?
A band near 3347 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 8 cited sources
Quick answer
A band near 3347 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) | 6 | 6 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| N h | 2 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| Water (H2O) | 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 |
|---|---|---|---|
| lignin | 3347, 1035, 1510 | Alkyl C-H, Hydroxyl (O-H) | 1 |
| GO | 3347, 1720, 1182 | Hydroxyl (O-H), 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 3347 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
“3a, the bands cm-1 at 3347 assigned as -OH stretching vibration is shifted to lower wavenumbers 3338 cm-1.”
Bian 等 - 2021 - Crystalline Structure Analysis of All-cellulose Na DOI: 10.1007/s10570-017-1259-0 -
Hydroxyl (O-H) confidence 1.0
“cm-1, cm-1, cm-1 (HOH bending), and three distinct peaks at 3347 3401 and 3505 (OH stretching in the metal hydroxide layer, or structurally bound water) [8,11,12];”
Comparison of ATR–FTIR and O-PTIR Imaging Techniques for the Characterisation of Zinc-Type Degradation Products in a Paint Cross-Section DOI: 10.3390/molecules27196301 -
Hydroxyl (O-H) confidence 1.0
“LLM confirmed rule peak-group candidate”
Giridhar 等 - 2017 - DIMENSIONAL STABILIZATION OF WOOD BY CHEMICAL MODI DOI: 10.4067/S0718-221X2017005000002 -
N h confidence 1.0
“The broad peak at 3347 is due to NH stretching band.”
Meng 等 - 2018 - Synthesis of Cationic Polyacrylamide Base on Low T DOI: 10.1063/1.5048740 -
Alkyl C-H confidence 1.0
“LLM confirmed rule peak-group candidate”
Sun 等 - 2014 - Preparation and Characterization of Poly(lactic ac DOI: 10.7317/pk.2014.38.4.464 -
Hydroxyl (O-H) confidence 1.0
“cm(cid:2)1 the bands at 3347 and 3463 which are attributed to the licensed on Raman bands are in agreement with those previously -OH -OH Published stretching vibration of groups (V O-H) either from reported.9,14,15”
Extracellular electron uptake from carbon-based π electron surface-donors: oxidation of graphite sheets by Sulfobacillus thermosulfidooxidans probed by Raman and FTIR spectroscopies DOI: 10.1039/c9ra03628h -
Alkyl C-H confidence 1.0
“(1006.5) 3102cm-1 Scaled and are assigned to C-H stretching as shown in CCH (43), 3347cm-1 (1043.85)”
Ullah 等 - 2013 - Terahertz Time Domain, Raman and Fourier Transform DOI: 10.1155/2013/148903 -
Hydroxyl (O-H) confidence 0.9
“Explicit assignment: '3347 cm-1 for isolated lignin' and 'O-H stretch' band region 3550-3200 cm-1.”
Enhancing Thermal and Mechanical Properties of Ramie Fiber via Impregnation by Lignin-Based Polyurethane Resin DOI: 10.3390/ma14226850
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