Asphaltene Molecular Size and Weight by Time-Resolved Fluorescence Depolarization

摘要: The most important attribute of any chemical compound is its elemental constituents. There is, fortunately, no uncertainty about the composition asphaltenes. second molecular structure and, as a prerequisite to that information, weight. Although set structures individual units constituting asphaltene, such number fused aromatic rings, length aliphatic chains, and common functional groups mostly agreed upon, asphaltene weight has been subject large long-standing controversy. For part, literature reports differ by factor 10, but some many orders magnitude. question essentially if how are linked. These uncertainties exacerbated corresponding possibilities different asphaltenes variable, thus prohibiting facile comparison results across laboratories on This controversy retarded development science in knowledge structure–function relations precluded unknown. Consequently, phenomenological approach routine science. We employ time-resolved fluorescence depolarization (TRFD) measure rotational correlation time variety TRFD methods naturally allow interrogation chromophore classes enabling stringent predictions be tested regarding structure. n-Heptane from virgin crude oils found have distribution with mean at ∼750 g/mol, FWHM 500 g/mol 1000 rapidly diminishing tail higher little variation among