What absorbs at 824 cm⁻¹ in an FTIR spectrum?
A band near 824 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 824 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 |
|---|---|---|---|
| Alkyl C-H | 7 | 7 | 1,0 |
| Aromatic ring | 2 | 2 | 1,0 |
| Carbon dioxide | 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 |
| Nitro (NO2) | 1 | 1 | 1,0 |
| Alkene (C=C) | 1 | 1 | 1,0 |
| C-S single bond | 1 | 1 | 1,0 |
| C c single bond | 1 | 1 | 1,0 |
| Hydroxyl (O-H) | 1 | 1 | 1,0 |
| Siloxane (Si-O-Si) | 1 | 1 | 1,0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1,0 |
| Silicon (Si) | 1 | 1 | 1,0 |
| Oxygen heterocycle | 1 | 1 | 1,0 |
| C=n | 1 | 0 | 1,0 |
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 |
|---|---|---|---|
| polyurethane | 824, 2270, 1700 | Alkyl C-H, N h | 1 |
| saliva | 824, 1648, 1664 | Alkyl C-H | 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 824 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
-
Oxygen heterocycle confiança 1,0
“LLM confirmed rule peak-group candidate”
Mudri 等 - 2020 - Comparative Study of Aromatic and Cycloaliphatic I DOI: 10.3390/polym12071494 -
Silicon (Si) confiança 1,0
“ences corresponding increase in absorption peaks at 824 and 1055 In the mean time, a non-porous sample (c-Si) showed insignificant to the Si O Si vibration mode.”
A combination of electroless and electrochemical etching methods for enhancing the uniformity of porous silicon substrate for light detection application DOI: 10.1016/j.apsusc.2012.03.056 -
Alkyl C-H confiança 1,0
“C-H rocking of pure PVA is considered the cm-1 peak at 824 [31].”
From Green Remediation to Polymer Hybrid Fabrication with Improved Optical Band Gaps DOI: 10.3390/ijms20163910 -
confiança 1,0
“The peaks at 746 and 824 cm-1 in the UiO-66 framework, Zr-µ3-OH stretching and OH bending modes, respectively [46].”
Butova 等 - 2023 - In Situ FTIR Spectroscopy for Scanning Accessible DOI: 10.3390/nano13101675 -
C c single bond confiança 1,0
“In the spectra obtained after the cut-off at 3 kDa, the only signals related to proteins are the out-of-ring breathing of cm-1), cm-1), tyrosine (824 the C-C stretching of the proline ring (926 the C-C stretching cm-1),”
The Role of the Preanalytical Step for Human Saliva Analysis via Vibrational Spectroscopy DOI: 10.3390/metabo13030393 -
Alkyl C-H confiança 1,0
“In order to perform semi-quantitative analyses, the peaks were normalised cm-1 using the peak located at ~824 attributed to the C-H deformation of the PPTA sequence aging duration.”
Derombise 等 - 2009 - Degradation of Technora aramid fibres in alkaline DOI: 10.1016/j.polymdegradstab.2009.07.021 -
Alkyl C-H confiança 1,0
“Figure 4: FTIR spectrum of as-received Technora T240 fibres cm-1 The peaks were normalised using the peak located at ~824 attributed to the C-H deformation of”
Influence of finish treatment on the durability of aramid fibers aged under an alkaline environment DOI: 10.1002/app.31534 -
C-S single bond confiança 1,0
“The peak cm-1 824 is responsible for the C-S stretching vibrations at 7.35 ppm (peak j) is attributed to the protons at position of thiophene structures.”
Doan 等 - 2022 - Synthesis of Conjugated Molecules Based on Dithien DOI: 10.21577/0103-5053.20220031
Tem um espectro com esta banda?
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