What absorbs at 3240 cm⁻¹ in an FTIR spectrum?
A band near 3240 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
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Hydroxyl (O-H) | 5 | 4 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| Carbohydrate | 1 | 1 | 0.7 |
| Silicon (Si) | 1 | 0 | 1.0 |
| Water (H2O) | 1 | 0 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Literature behind these assignments
-
Carboxyl (COOH) confidence 1.0
“[14] reported the band at 3240 could be attributed to carboxylic 6 acid formation.”
A study of molecular architectural dynamics of crosslinked urethane during photo-aging by two-dimensional infrared correlation spectroscopy DOI: 10.1016/j.polymdegradstab.2020.109242 -
Hydroxyl (O-H) confidence 1.0
“81.5)andhasalargeabsorptionbandcenteredaround3240cm-1inGroupIIintheγdirection.SLP114isuniquein SLP400hasFe-richolivines(Fo having its main OH-absorption peaks in Group II.”
Peslier 和 Luhr - 2006 - Hydrogen loss from olivines in mantle xenoliths fr DOI: 10.1016/j.epsl.2005.12.019 -
confidence 1.0
“At high frequencies, a broad and strong absorption cm-1 cm-1 and 3240 is detected indicating the presence of showing two maxima at ca.”
Augugliaro 等 - 2008 - Photocatalytic oxidation of aromatic alcohols to a DOI: 10.1016/j.apcata.2008.07.038 -
Hydroxyl (O-H) confidence 1.0
“The first set of spectral attributes includes bands assigned to O-containing functional cm-1 groups: (a) The broad absorption band centered at about 3240 corresponds to O-H stretching of various functional groups (including the carboxylic),”
Polarity-Based Sequential Extraction as a Simple Tool to Reveal the Structural Complexity of Humic Acids DOI: 10.3390/agronomy11030587 -
Hydroxyl (O-H) confidence 1.0
“Thus, the Here, it should be noted that the bands at 3488 3447 cm-1 band at 3345 (O H stretch of cellulose type I) (Moharram & assigned for OH stretching intramolecular hydrogen bonding as cm-1 2008) and the band at 3240 (stretching of hydr”
Komagataeibacter rhaeticus as an alternative bacteria for cellulose production DOI: 10.1016/j.carbpol.2016.06.049 -
confidence 1.0
“Explicit: 'bands at 3240, 3036 and 2809 are components of H-bond between H- and N-H'”
Remarkable acid strength of ammonium ions in zeolites: FTIR study of low-temperature CO adsorption on NH4FER DOI: 10.1039/c4ra12504e -
Hydroxyl (O-H) confidence 0.8
“Assigned to water in context.”
Comprehensive Studies on the Role of Small Aliphatic Alcohols in the Direct Synthesis of Hydrogen Peroxide with a Combination of Solvent Step and In Situ FTIR-ATR Experiments DOI: 10.3390/catal13040753 -
Carbohydrate confidence 0.7
“Text: 'bands manifested at 3240 and 3270 affirm the existence of both' cellulose I and II.”
A turning point in the bacterial nanocellulose production employing low doses of gamma radiation DOI: 10.1038/s41598-022-11010-4
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