What absorbs at 678 cm⁻¹ in an FTIR spectrum?
A band near 678 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 5 cited sources
Hurtigt svar
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.
Mulige funktionelle gruppetildelinger
| Funktionel gruppe | Understøttende fakta | Citerede kilder | Højeste tillid |
|---|---|---|---|
| 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 |
Rangering afspejler akkumulerede litteraturbeviser, ikke en enkelt autoritativ regel. Bekræft altid mod din prøvekontekst.
Spektrumlogik
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.
Anvendelse i virkeligheden
Denne type forespørgsel er almindelig ved polymeridentifikation, screening af ukendt plast, fejlfinding i kvalitetskontrol, verifikation af genanvendt materiale og litteraturunderstøttet gennemgang af peak-tildeling.
Almindelige fejl
- Behandling af et isoleret bånd som bevis på et materiale uden at kontrollere mindst en eller to understøttende toppe.
- Ignorerer overlap: flere funktionelle grupper kan bidrage nær samme bølgetal.
- Spring validering over, når additiver, blandinger, oxidation eller forurening kan forvrænge spektret.
Verifikationsrådgivning
Når tvetydighed fortsat består, valider hypotesen med DSC, GC-MS eller TGA, især for blandinger, nedbrudte prøver og fyldte polymerer.
Litteratur bag disse tildelinger
-
tillid 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 tillid 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 tillid 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) tillid 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 tillid 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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