Molecular orientation of asphaltenes and PAH model compounds in langmuir-blodgett films using sum frequency generation spectroscopy

A. Ballard Andrews, Arthur McClelland, Oona Korkeila, Alexander Demidov, Amber Krummel, Oliver C. Mullins, Zhan Chen

    Research output: Contribution to journalArticleScientificpeer-review

    87 Citations (Scopus)

    Abstract

    Asphaltenes are an important class of compounds in crude oil whose surface activity is important for establishing reservoir rock wettability which impacts reservoir drainage.While many phenomenological interfacial studies with crude oils and asphaltenes have been reported, there is very little known about themolecular level interactions between asphaltenes and mineral surfaces. In this study, we analyze Langmuir-Blodgett films of asphaltenes and related model compounds with sum frequency generation (SFG) vibrational spectroscopy. In SFG, the polarization of the input (vis, IR) and output (SFG) beams can be varied, which allows the orientation of different functional groups at the interface to be determined. SFG clearly indicates that asphaltene polycyclic aromatic hydrocarbons (PAHs) are highly oriented in the plane of the interface and that the peripheral alkanes are transverse to the interface. In contrast, model compounds with oxygen functionality have PAHs oriented transverse to the interface. Computational quantumchemistry is used to support corresponding band assignments, enabling robust determination of functional group orientations.

    Original languageEnglish
    Pages (from-to)6049-6058
    Number of pages10
    JournalLangmuir
    Volume27
    Issue number10
    DOIs
    Publication statusPublished - 1 Jun 2011
    MoE publication typeA1 Journal article-refereed

    Fingerprint Dive into the research topics of 'Molecular orientation of asphaltenes and PAH model compounds in langmuir-blodgett films using sum frequency generation spectroscopy'. Together they form a unique fingerprint.

    Cite this