What absorbs at 678 cm⁻¹ in an FTIR spectrum?
Una banda cerca de 678 cm⁻¹ puede apuntar a varios grupos funcionales. A continuación se muestran las asignaciones más probables, clasificadas por cuánta evidencia publicada respalda cada una — cada una trazable a literatura (DOI) y validada de forma cruzada con nuestros más de 130,000 espectros de referencia y grafo de conocimiento.
Backed by 5 cited sources
Quick answer
A band near 678 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.
Posibles asignaciones de grupos funcionales
| Grupo funcional | Hechos de respaldo | Fuentes citadas | Confianza máxima |
|---|---|---|---|
| Silicon-oxygen (Si-O) | 2 | 1 | 1,0 |
| C-S single bond | 2 | 1 | 1,0 |
| Metal oxygen | 2 | 1 | 1,0 |
| Carbon bromine | 1 | 1 | 1,0 |
| Ring structure | 1 | 1 | 1,0 |
| C c single bond | 1 | 1 | 1,0 |
| Alkyl C-H | 1 | 1 | 0,8 |
| Silicon (Si) | 1 | 0 | 1,0 |
| Siloxane (Si-O-Si) | 1 | 0 | 1,0 |
La clasificación refleja la evidencia acumulada de la literatura, no una única regla autorizada. Siempre confirme según el contexto de su muestra.
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 678 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.
Literatura detrás de estas asignaciones
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confianza 1,0
“2014), whereas two small bands A cm-1 positioned at 678 and 618 are linked to Ag-O (Kumar and Rani 2013;”
Haq 等 - 2018 - Fabrication of pure and moxifloxacin functionalize DOI: 10.1016/j.jphotobiol.2018.07.011 -
C c single bond confianza 1,0
“24 25 cm-1 A small peak observed at 678 is C-C out of plane ring deformation or C-H rocking [28].”
Velhal 等 - 2018 - Structural, electrical and microwave properties of DOI: 10.1088/2053-1591/aadaf7 -
C-S single bond confianza 1,0
“In cm-1 cm-1 this Raman spectra peaks at 678 and 713 are attributed to C-S symmetric and cm-1 antisymmetric stretches, and the peak at 1000 is assigned to the S=O stretch.”
Origin of Defects and Positron Annihilation in Hybrid and All-Inorganic Perovskites DOI: 10.1021/acs.chemmater.1c03540 -
Silicon-oxygen (Si-O) confianza 1,0
“styreneSi-O-Si), Si-CH However, the analysis suggests that the material could be 3), 1101 (asymmetric stretching of 1068 (asymmetric Si-O-Si), Si-O-Si), stretching of 806 (symmetric stretching of 678 butadienerubber(SBR)becausesignalsofsuch”
Non-invasive identification of plastic materials in museum collections with portable FTIR reflectance spectroscopy: Reference database and practical applications DOI: 10.1016/j.microc.2015.07.016 -
Carbon bromine confianza 1,0
“LLM confirmed rule peak-group candidate”
Setyawati 等 - 2017 - Synthesis and Characterization of Novel Benzohydra DOI: 10.1063/1.4978194
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