NEXAFS and XPS of p-Aminobenzoic Acid Polymorphs: The Influence of Local Environment

Joanna Stevens, Adrian Gainar, Cherno Jaye, Daniel A Fischer, Sven L. M. Schroeder

    Research output: Contribution to journalArticlepeer-review


    Nitrogen K-edge XPS and NEXAFS of the two polymorphic forms of para- aminobenzoic acid (PABA) are significantly different reflecting variation in hydrogen bonding. Alteration in hydrogen bonding at the amino group leads to a shift to high energy for both the XPS N 1s core level and the 3π* NEXAFS resonance with β-PABA. Participation of the amine group in the aromatic system causes the 1π* resonance to be sensitive to the nature of the intermolecular bonding at the para-carboxylic acid group, and a shift to low energy for α- PABA is observed due to hydrogen-bonded carboxylic acid dimer formation. FEFF calculations also successfully reproduce both the energy and intensity variations observed for the σ* shape resonance associated with the C-N bond, with the majority of the decrease in energy observed for b-PABA arising from the longer C-N bond.
    Original languageEnglish
    Article number012133
    JournalJournal of Physics: Conference Series
    Publication statusPublished - 2016


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