What absorbs at 841 cm⁻¹ in an FTIR spectrum?
A band near 841 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
Resposta rápida
A band near 841 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.
Possíveis atribuições de grupos funcionais
| Grupo funcional | Fatos de suporte | Fontes citadas | Maior confiança |
|---|---|---|---|
| Methoxy (OCH3) | 5 | 5 | 1,0 |
| Methacrylate | 5 | 5 | 1,0 |
| C-O single bond | 5 | 5 | 1,0 |
| Acetate | 5 | 5 | 1,0 |
| C c single bond | 4 | 4 | 1,0 |
| Ring structure | 3 | 3 | 1,0 |
| Alkyl C-H | 3 | 2 | 1,0 |
| Carbohydrate | 2 | 2 | 1,0 |
| Metal oxygen | 1 | 1 | 1,0 |
| Nitrogen heterocycle | 1 | 1 | 1,0 |
| Alkene (C=C) | 1 | 1 | 1,0 |
| Nucleic acid | 1 | 1 | 1,0 |
| Fluorine (C-F) | 1 | 1 | 0,9 |
A classificação reflete a evidência acumulada da literatura, não uma única regra autoritária. Sempre confirme com o contexto da sua amostra.
Materiais possíveis
| Material | Picos de suporte | Grupos sobrepostos | Fontes citadas |
|---|---|---|---|
| polypropylene | 841, 1030, 1600 | Methacrylate, Acetate, Methoxy (OCH3) | 1 |
| chitosan | 841, 1650, 1655 | Acetate, Methacrylate, C-O single bond | 1 |
| cotton | 841, 1030, 1638 | Methacrylate, Acetate, C-O single bond | 1 |
Os materiais são mostrados apenas quando o mesmo conjunto de literatura suporta esta banda e pelo menos um pico característico adicional.
Lógica do espectro
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 841 cm⁻¹ is usually not enough for material identification by itself.
Uso no mundo real
Este tipo de consulta é comum em identificação de polímeros, triagem de plásticos desconhecidos, solução de problemas de CQ, verificação de materiais reciclados e revisão de atribuição de picos apoiada pela literatura.
Erros comuns
- Tratar uma banda isolada como prova de um material sem verificar pelo menos um ou dois picos de suporte.
- Ignorando sobreposição: vários grupos funcionais podem contribuir próximo ao mesmo número de onda.
- Ignorar a validação quando aditivos, misturas, oxidação ou contaminação podem distorcer o espectro.
Conselho de verificação
Quando a ambiguidade persistir, valide a hipótese com DSC, GC-MS ou TGA, especialmente para misturas, amostras degradadas e polímeros carregados.
Literatura por trás destas atribuições
-
C c single bond confiança 1,0
“The ~841 band is assigned to tained two-dimensional pattern employing a data processing software, C-C the vibration coupling of stretching, CH2 rocking, and CH3 rocking”
Probing the difference of crystalline modifications and structural disorder of isotactic polypropylene via high-resolution FTIR spectroscopy DOI: 10.1016/j.polymer.2021.123722 -
Nucleic acid confiança 1,0
“The presence of B-DNA and Z-DNA bands at 841 and 815 suggested that only the Z-DNA form is more pronounced in melanoma, whereas both DNA forms were detected in BCC [92].”
Vibrational Spectroscopy Fingerprinting in Medicine: from Molecular to Clinical Practice DOI: 10.3390/ma12182884 -
C c single bond confiança 1,0
“at 841 cm-1 and 1168 cm-1,corresponding to C-C isopropyl stretching;”
From Waste to Potential Reuse: Mixtures of Polypropylene/Recycled Copolymer Polypropylene from Industrial Containers: Seeking Sustainable Materials DOI: 10.3390/su14116509 -
Acetate confiança 1,0
“In κ-carrageenan, the vibrations from 841, 921 and 1035 cm-1 and 1035 could be assigned to -C-O-SO 3stretching vibrations from the galactose-4-sulphate, cm-1 could be assigned to -C-O-SO3stretching vibrations from the galactose-4-sulphate,”
Croitoru 等 - 2020 - Physically Crosslinked Poly (Vinyl Alcohol)Kappa- DOI: 10.3390/polym12030560 -
Carbohydrate confiança 1,0
“The band α-anomer of 841 represents the functional groups of polysaccharides include also the in the pyranose form of sugars.”
Egyptian Opuntia ficus-indica (OFI) Residues: Recovery and Characterization of Fresh Mucilage from Cladodes DOI: 10.3390/horticulturae9070736 -
Carbohydrate confiança 1,0
“Finally, absorptions at 944 cm-1 and 841 cm-1 were assigned to the pyranose ring.”
Gabriela Chuc-Gamboa 等 - 2021 - Antibacterial Behavior of Chitosan-Sodium Hyaluron DOI: 10.3390/app1103 -
Alkene (C=C) confiança 1,0
“A peak at 1228 indicates cm-1 a strong CO bond, and a peak at 841 indicates a bending C=C bond of the alkene.”
Grgac 等 - 2022 - The Effect of Ultrasonic Treatment on the Binding DOI: 10.3390/ma15020470 -
Alkyl C-H confiança 1,0
“rock, C-C stretch 1165 CH bend, CH 3 rock, CH bend 996 CH bend, CH 3 3 rock, C-CH stretch 841 CH 2 3 rock, C-C stretch, C-CH stretch 809 CH 2 2915 CH stretch Polyethylene (PE) (Asensio et al., 2009;”
Malla-Pradhan 等 - 2022 - Occurrence and Distribution of Microplastics from DOI: 10.1007/s11270-022-05896-z
Tem um espectro com esta banda?
Carregue seu espectro FTIR e obtenha um relatório de interpretação completo — atribuições de picos com citações da literatura, correspondências de biblioteca e uma cadeia de evidências com nível de confiança — em segundos.