What absorbs at 402 cm⁻¹ in an FTIR spectrum?
A band near 402 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 4 cited sources
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| N-O bond | 2 | 1 | 1.0 |
| Ammonium | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Quaternary ammonium | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 0 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Literature behind these assignments
-
Quaternary ammonium confidence 1.0
“Simon Christian aMBIE The Biocide Toolbox Programme, The University of Auckland, Private Bag 92019, Auckland 1042, New Zealand bSchool of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1042, New Zealand cDepartme”
Anchored quaternary ammonium salts adsorbed on polyurethane film surfaces DOI: 10.1016/j.porgcoat.2019.105343 -
C-O single bond confidence 1.0
“Among 401 cm-1 them, the absorption at 1044 was mainly attributed to C-O stretching on C-O-C 402”
Beltramino 等 - 2016 - Optimization of sulfuric acid hydrolysis condition DOI: 10.1007/s10570-016-0897-y -
Ammonium confidence 1.0
“The peak at 402.2 eV is probably due to the positively charged ammonium in lysine.”
Torres-Gonzalez 等 - 2018 - Characterization of Recombinant His-Tag Protein Im DOI: 10.3390/s18124262 -
N-O bond confidence 1.0
“As shown in the lower graph, the samples not subjected to preconditioning have no peak, whereas the samples subjected to preconditioning have a peak at 402 or 400 eV.”
Analysis of a Lipid/Polymer Membrane for Bitterness Sensing with a Preconditioning Process DOI: 10.3390/s150922439
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