What absorbs at 790 cm⁻¹ in an FTIR spectrum?
A band near 790 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 790 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 |
|---|---|---|---|
| Silicon-oxygen (Si-O) | 12 | 11 | 1.0 |
| Silicon (Si) | 8 | 8 | 1.0 |
| Metal oxygen | 6 | 5 | 1.0 |
| Siloxane (Si-O-Si) | 5 | 5 | 1.0 |
| Hydroxyl (O-H) | 4 | 4 | 1.0 |
| Silicon carbon | 4 | 4 | 1.0 |
| Alkyl C-H | 4 | 4 | 1.0 |
| N h | 3 | 3 | 1.0 |
| Water (H2O) | 3 | 3 | 1.0 |
| Secondary amine | 2 | 2 | 1.0 |
| Aromatic ring | 2 | 2 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
| Carbonate | 1 | 1 | 1.0 |
| Amine primary | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Chlorine | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Thiol | 1 | 0 | 1.0 |
| C-S single bond | 1 | 0 | 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 |
|---|---|---|---|
| ZnO | 790, 1400, 3430 | Metal oxygen | 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 790 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
-
Aromatic ring confidence 1.0
“benzenoid ring, it gives a small band at 790 Furthermore, in PANI-ECMA”
Synthesis of novel conducting polyaniline composites based on seaweed Enteromorpha compressa macro-alga powder DOI: 10.1007/s00289-020-03191-7 -
Carboxyl (COOH) confidence 1.0
“Short-term acid leaching of palygorskitesresultsinsignificantchangestoFTIRabsorptionbandsnear1200and790cm-1.Astheacidattackprogresses,thebandat1200cm-1 790cm-1, shifts to lower wavenumbers, whilst the band at which here is assigned to Si U-”
Cai 等 - 2007 - A Fourier transform infrared spectroscopic study o DOI: 10.1016/j.saa.2006.02.053 -
Metal oxygen confidence 1.0
“Infrared bands at 790 and 872 and As assigned to the symmetric stretching vibrations of As-O.”
Fan 和 Zhang - 2019 - ATR-FTIR spectroscopic characterization of ferric DOI: 10.5004/dwt.2019.23721 -
C c single bond confidence 1.0
“The peak cm-1 at 790 can be assigned to the C-C stretch vibration of alkyl halides.”
Hieu 等 - 2022 - Microorganism-mediated green synthesis of silver n DOI: 10.15251/DJNB.2022.171.359 -
Silicon carbon confidence 1.0
“The peaks around 1,260 and cm-1 Si-OH groups that reduce the condensation reaction and 790 are for the absorption from Si-CH [9].”
Ingale 等 - 2011 - Physico-chemical properties of silica aerogels pre DOI: 10.1007/s10934-010-9410-4 -
Amide confidence 1.0
“cm-1 (in-ring) stretch aromatics, 1,381.60 stands for cm-1 C-C C-N developed for and stretching, 1,087.11 cm-1 C-N stands for stretch (aliphatic amines) and 789.55 Fig.”
Marimuthu 等 - 2012 - Lousicidal activity of synthesized silver nanopart DOI: 10.1007/s00436-011-2667-y -
Alkyl C-H confidence 1.0
“group frequencies, nine fundaFor the assignments of CH Thestrongpeaksbelow960cm-1,i.e.,around790and850cm-1 3 mentals can be associated to each CH group [59], namely, CH 3 3 clearly indicate its aromatic nature.”
FTIR and FT Raman, molecular geometry, vibrational assignments, ab initio and density functional theory calculations for 1,5-methylnaphthalene DOI: 10.1016/j.saa.2010.09.002 -
confidence 1.0
“On the other hand, cm-1 bands at 643, 700 and 790 cm-1 correspond to the Zn-OH group [30].”
Rapid Bio-Assisted Synthesis and Magnetic Behavior of Zinc Oxide/Carbon Nanoparticles DOI: 10.3390/cryst13071081
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