What absorbs at 996 cm⁻¹ in an FTIR spectrum?
A band near 996 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 996 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 |
|---|---|---|---|
| C-O single bond | 5 | 3 | 1.0 |
| Methoxy (OCH3) | 4 | 3 | 1.0 |
| Methacrylate | 4 | 3 | 1.0 |
| Acetate | 4 | 3 | 1.0 |
| C c single bond | 3 | 3 | 1.0 |
| Alkyl C-H | 3 | 2 | 1.0 |
| Aromatic ring | 2 | 2 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Metal oxo | 1 | 1 | 1.0 |
| Metal oxygen | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Hydrogen bond | 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 |
|---|---|---|---|
| HCl | 996, 1708, 1032 | Methacrylate, C-O single bond, Acetate | 1 |
| montmorillonite | 996, 1637, 523 | Methacrylate, Acetate | 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 996 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
-
Hydrogen bond confidence 1.0
“Rheometer-Fourier transform infrared cm(cid:0) 1 (FTIR) spectroscopy showed that the C-6 peak at 996 for all the samples was displaced or disappeared due to the hydrogen bond fracture caused by water molecules entering the starch granules.”
Effect of gliadin/glutenin ratio on pasting, thermal, and structural properties of wheat starch DOI: 10.1016/j.jcs.2020.102973 -
Carboxyl (COOH) confidence 1.0
“The 996 peak is most likely unreacted fixed to test this would be to run more experiments at pressure and formic acid.”
Reactions between organic acids and montmorillonite clay under Earth-forming conditions DOI: 10.1016/j.chemgeo.2010.12.023 -
Metal oxygen confidence 1.0
“The band at 996 is assigned to V O stretching of distorted octahedral and distorted cm-1 square pyramids, while the band at 702 is due to coordination of vanadium atoms with the three oxygen”
Vanadium pentoxide nanobelts: One pot synthesis and its lithium storage behavior DOI: 10.1002/crat.201200122 -
Metal oxo confidence 1.0
“and The stretching and bending modes of V-O generate peaks at 705 cm-1 and the shift at 996 cm-1 is due to stretching mode of V=O [21].”
Saravanakumar 等 - 2018 - Role of NaOH concentration on synthesis and charac DOI: 10.1063/1.5047993 -
confidence 1.0
“were observed, and the energies of the main oxygen peaks 996 E.A.”
Abou Neel 等 - 2009 - Doping of a high calcium oxide metaphosphate glass DOI: 10.1016/j.jnoncrysol.2009.04.016 -
C c single bond confidence 1.0
“The peak observed at 996 is due to C-C”
Influence of most reactive inorganic cation in the optical and biological activities of L-Lysine monohydrochloride crystal DOI: 10.1016/j.sjbs.2020.07.018 -
Alkyl C-H confidence 1.0
“The Raman line at 996 cm-1 (Figup-shift of the Raman line assigned to the C-H bending vibrational mode in the benzene ure 1a) belongs to the vibrational modes of W=O in the H 4SiW 12O [17].”
Optical Evidence for the Assembly of Sensors Based on Reduced Graphene Oxide and Polydiphenylamine for the Detection of Epidermal Growth Factor Receptor DOI: 10.3390/coatings11020258 -
Aromatic ring confidence 1.0
“hPH-a hBA-a peaks, as follows: the 1600 line in both and corresponds to the monosubstituted cm-1 benzene ring while 996 is the vibration of the disubstituted and trisubstituted benzene rings in hPH-a hBA-a, hPH-a and respectively.”
Developing Further Versatility in Benzoxazine Synthesis via Hydrolytic Ring-Opening DOI: 10.3390/polym12030694
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