What absorbs at 775 cm⁻¹ in an FTIR spectrum?
A band near 775 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 775 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.
Attributions possibles de groupes fonctionnels
| Groupe fonctionnel | Faits à l＇appui | Sources citées | Confiance maximale |
|---|---|---|---|
| Alkyl C-H | 4 | 4 | 1,0 |
| Amide | 3 | 3 | 1,0 |
| Aromatic ring | 2 | 2 | 1,0 |
| Silicon-oxygen (Si-O) | 2 | 2 | 1,0 |
| Methacrylate | 2 | 2 | 1,0 |
| Acetate | 2 | 2 | 1,0 |
| Silicon (Si) | 2 | 1 | 1,0 |
| Thiocarbonyl | 1 | 1 | 1,0 |
| N h | 1 | 1 | 1,0 |
| Secondary amine | 1 | 1 | 1,0 |
| C n single bond | 1 | 1 | 1,0 |
| Methoxy (OCH3) | 1 | 1 | 1,0 |
| C-O single bond | 1 | 1 | 1,0 |
| Ring structure | 1 | 1 | 1,0 |
| C c single bond | 1 | 1 | 1,0 |
| Alkene (C=C) | 1 | 1 | 1,0 |
| Phosphate (PO4) | 1 | 1 | 1,0 |
| Chlorine | 1 | 1 | 1,0 |
| Ketone | 1 | 1 | 1,0 |
| Ester | 1 | 1 | 1,0 |
| Carboxyl (COOH) | 1 | 1 | 1,0 |
| Carbonyl (C=O) | 1 | 1 | 1,0 |
Le classement reflète les preuves bibliographiques accumulées, et non une règle faisant autorité. Confirmez toujours dans le contexte de votre échantillon.
Possible materials
| Matériel | Pics de support | Overlapping groups | Sources citées |
|---|---|---|---|
| silver nanoparticles | 775, 1636, 1631 | Alkyl C-H, Amide | 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 775 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.
Bibliographie derrière ces attributions
-
Acetate confiance 1,0
“TC-DO at 1412 and 779 W-DM had characteristic peaks at 1723 (C=O vibration), 1514, cm-1 corresponding to the characteristic peaks of TC-DM at 1643, 1465, 1413, 1456, 1422 and 775 cm-1.”
Discrimination and similarity evaluation of tissue-cultured and wild Dendrobium species using Fourier Transform Infrared Spectroscopy DOI: 10.1016/j.molstruc.2015.01.027 -
confiance 1,0
“6 FTIR spectra for a b c and of SPEs 16:2251-2260 2258 J Solid State Electrochem (2012) cm-1 8.0×10-8 cm-1 C-Cl functional group of stretching at 775 for aliphatS is obtained at 15% wt.”
Lee 等 - 2012 - Temperature dependence of the conductivity of plas DOI: 10.1007/s10008-011-1633-z -
Phosphate (PO4) confiance 1,0
“In the metaphosphate 775cm-1, (P-O-P) and (P-O-P) bands at about 900 and glass composition, CuO primarily acts as network modias s 43Q2 groups respectively, and the deformation modes of PO fier to depolymerize phosphate chain, until all the”
Shih 等 - 2003 - P-31 MAS-NMR and FTIR analyses on the structure of DOI: 10.1016/S0254-0584(03)00098-1 -
Alkene (C=C) confiance 1,0
“1624 Strong (methyne) 775 Medium Alkenyl C=C stretch Olefinic alkene 1458 Medium C=C-C aromatic ring stretch 775 Medium Alkenyl C=C stretch”
The Antimicrobial Activities of Silver Nanoparticles from Aqueous Extract of Grape Seeds against Pathogenic Bacteria and Fungi DOI: 10.3390/molecules26196081 -
Amide confiance 1,0
“The third (1239 and fourth cm-1) (775 amide band can be clearly seen only for PSi0, because in the PSi samples those bands are overlapped by the stronger aforementioned bands”
Thermal and surface properties of hybrid materials obtained from epoxy-functional urethane and siloxane DOI: 10.1007/s00289-015-1545-7 -
Acetate confiance 1,0
“(C-H 3308 stretching vibration), 2933 stretching of CH2 group), recorded in native nanocomposite components, were assigned corre- - O-H C-H 1602 (COOH stretching), 1429 (uronic acid (COOH)), 1018 825 sponding to stretching vibration at 3292”
Green decoration of graphene oxide Nano sheets with gelatin and gum Arabic for targeted delivery of doxorubicin DOI: 10.1016/j.btre.2022.e00722 -
Amide confiance 1,0
“a major peak has appeared at 775 These peaks were characteristic of C-N stretch (amines), =C-H bend (benzene, alkenes), and C-C (chlorides).”
Potential of Suaeda nudiflora and Suaeda fruticosa to Adapt to High Salinity Conditions DOI: 10.3390/horticulturae9010074 -
Thiocarbonyl confiance 1,0
“The following inference are made from the Cd2+, concentration of free as much of these ions would be in cm-1 found for pure observed FTIR results,The band at 775 42complex and most of the allylthiourea the form of CdCl Allylthiourea is assi”
Perumal 等 - 2023 - Influence of pH on the Growth of Tris-Allylthioure DOI: 10.14447/jnmes.v26i2.a07
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