What absorbs at 3138 cm⁻¹ in an FTIR spectrum?
A band near 3138 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
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Alkyl C-H | 2 | 2 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Ammonium | 1 | 1 | 0.95 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Literature behind these assignments
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Aromatic ring confidence 1.0
“cm-1 The functional groups for synthesized ZnO NPs were 3852 for H-H weak peak, cm-1 cm-1 3138 for aromatic C-H extend, and 1648 for Aromatic ring stretch.”
An Investigation of the Cytotoxicity and Caspase-Mediated Apoptotic Effect of Green Synthesized Zinc Oxide Nanoparticles Using Eclipta prostrata on Human Liver Carcinoma Cells DOI: 10.3390/nano5031317 -
Alkyl C-H confidence 1.0
“The strong and sharp peak at 3138 cm-1 indicates C-H bonding that is likely to be from the methyl group of DMSO2.”
The Green Synthesis of 2D Copper Nanosheets and Their Light Absorption DOI: 10.3390/ma14081926 -
Ammonium confidence 0.95
“Explicit assignment in text: '3138 cm-1 NH3+ (N-H stretch)'”
Szostak 等 - 2019 - Nanoscale mapping of chemical composition in organ DOI: 10.1126/sciadv.aaw6619
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