What absorbs at 845 cm⁻¹ in an FTIR spectrum?
A band near 845 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
Risposta rapida
A band near 845 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.
Possibili assegnazioni di gruppi funzionali
| Gruppo funzionale | Fatti di supporto | Fonti citate | Affidabilità massima |
|---|---|---|---|
| Methoxy (OCH3) | 3 | 2 | 1,0 |
| Silicon-oxygen (Si-O) | 2 | 2 | 1,0 |
| Alkyl C-H | 2 | 2 | 1,0 |
| Silicon carbon | 2 | 2 | 1,0 |
| Metal oxygen | 2 | 2 | 1,0 |
| C c single bond | 2 | 2 | 1,0 |
| Carbohydrate | 2 | 2 | 1,0 |
| Methacrylate | 2 | 2 | 1,0 |
| Acetate | 2 | 2 | 1,0 |
| C-O single bond | 2 | 2 | 1,0 |
| Fluorine (C-F) | 1 | 1 | 1,0 |
| Silicon (Si) | 1 | 1 | 1,0 |
| Hydroxyl (O-H) | 1 | 1 | 1,0 |
| Phosphate (PO4) | 1 | 1 | 1,0 |
| Secondary amine | 1 | 1 | 1,0 |
| C n single bond | 1 | 1 | 1,0 |
| Amide | 1 | 1 | 1,0 |
| Ring structure | 1 | 1 | 1,0 |
| Aromatic ring | 1 | 1 | 1,0 |
| Sulfate (SO4) | 1 | 1 | 1,0 |
| N n bond | 1 | 1 | 1,0 |
| Oxygen heterocycle | 1 | 1 | 0,9 |
La classifica riflette le prove bibliografiche accumulate, non una singola regola autorevole. Conferma sempre nel contesto del tuo campione.
Materiali possibili
| Materiale | Picchi di supporto | Gruppi sovrapposti | Fonti citate |
|---|---|---|---|
| polypyrrole | 845, 1700, 400 | Alkyl C-H | 1 |
| PPy | 845, 1043, 910 | Alkyl C-H, Methoxy (OCH3) | 1 |
| PVA | 845, 1660, 2930 | Alkyl C-H, Methoxy (OCH3) | 1 |
I materiali vengono mostrati solo quando lo stesso pool di letteratura supporta questa banda e almeno un picco caratteristico aggiuntivo.
Logica dello spettro
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 845 cm⁻¹ is usually not enough for material identification by itself.
Utilizzo nel mondo reale
Questo tipo di richiesta è comune nell＇identificazione dei polimeri, nello screening di plastiche sconosciute, nella risoluzione dei problemi di controllo qualità, nella verifica dei materiali riciclati e nella revisione dell＇assegnazione dei picchi supportata dalla letteratura.
Errori comuni
- Trattare una banda isolata come prova di un materiale senza verificare almeno uno o due picchi di supporto.
- Ignorando la sovrapposizione: più gruppi funzionali possono contribuire vicino allo stesso numero d＇onda.
- Saltare la convalida quando additivi, miscele, ossidazione o contaminazione possono distorcere lo spettro.
Consiglio di verifica
Quando permangono ambiguità, convalida l＇ipotesi con DSC, GC-MS o TGA, specialmente per miscele, campioni degradati e polimeri caricati.
Letteratura dietro queste assegnazioni
-
Acetate affidabilità 1,0
“Raw MPF spectrum shows a broad peak at cm-1 cm-1 at 845 is due to the deformation vibration of C-O-C 3395 of O-H stretching.”
Graft copolymerization of methyl methacrylate on Meizotropis Pellita fibres and their applications in oil absorbency DOI: 10.1007/s13726-020-00869-7 -
N n bond affidabilità 1,0
“The bands at (n n cm-1 845 and 971 and are due to stretching vibrations of SiO and 3) and bands at 486 and N 4 1”
Driving the photoluminescent and structural properties of X2-Y2SiO5 by varying the dopant Dy3+ concentration towards cool wLED applications DOI: 10.1016/j.solidstatesciences.2017.05.008 -
Metal oxygen affidabilità 1,0
“The FTIR spectrum showed the absorption band at 845 cm-1 that is due to the stretching mode of is attributed to Bi-O-Bi bond, and the strong absorption band recorded at 424 Bi-O.”
Zulkifli 等 - 2017 - Effect of Hydrothermal Reaction Time on Size of Bi DOI: 10.1063/1.5010448 -
C-O single bond affidabilità 1,0
“PVAL was observed via its C-O stretching vibrations and contributed as vibrations and contributed as a shoulder of the band at 1170 cm-1 with its C-C-O cm-1 cm-1 a shoulder of the band at 1170 with its C-C-O stretching at 845 [26].”
Polypyrrole Aerogels: Efficient Adsorbents of Cr(VI) Ions from Aqueous Solutions DOI: 10.3390/gels9070582 -
Sulfate (SO4) affidabilità 1,0
“Vibration bands at 830 and 845 cm-1 have previously been associated with 4-Oand 2-O-sulfate groups in agar-type polysaccharides [46].”
Exopolysaccharides Production by Cultivating a Bacterial Isolate from the Hypersaline Environment of Salar de Uyuni (Bolivia) in Pretreatment Liquids of Steam-Exploded Quinoa Stalks and Enzymatic Hydrolysates of Curupaú Sawdust DOI: 10.3390/fermentation7010033 -
Aromatic ring affidabilità 1,0
“and aromatic ring vibrations at 971, 870 and 845 cm-1 (Figcm-1;”
Advantages of External Reflection and Transflection over ATR in the Rapid Material Characterization of Negatives and Films via FTIR Spectroscopy DOI: 10.3390/polym14040808 -
affidabilità 1,0
“The IR band at 845 shows the Leal et al.”
Fernando 等 - 2017 - FTIR characterization and antioxidant activity of DOI: 10.4490/algae.2017.32.12.1 -
C c single bond affidabilità 1,0
“cm-1 C-C C-O 1140 is due to the stretching of the and groups [53,54], the 1092 signal corresponds cm-1 C-O to the stretching of the group and the 845 stretch vibration corresponds to the C-C [54].”
Judith Valdez-Alegria 等 - 2020 - Synthesis of Chitosan-Polyvinyl Alcohol Biopolymer DOI: 10.3390/biom10010156
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