1. NEXAFS Chemical State and Bond Lengths of p-Aminobenzoic Acid in Solution and Solid State
- Author
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Edlira Suljoti, Adrian Gainar, Sven L. M. Schroeder, Jie Xiao, Emad F. Aziz, Ronny Golnak, and Joanna S. Stevens
- Subjects
0303 health sciences ,History ,02 Physical Sciences ,010405 organic chemistry ,Chemistry ,030303 biophysics ,Analytical chemistry ,Cationic polymerization ,Large scale facilities for research with photons neutrons and ions ,01 natural sciences ,Bond order ,XANES ,Spectral line ,09 Engineering ,0104 chemical sciences ,Computer Science Applications ,Education ,Bond length ,03 medical and health sciences ,Chemical state ,Chemical species ,Crystallography ,Ionization energy - Abstract
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 3 p * NEXAFS resonance with b -PABA. Participation of the amine group in the aromatic system causes the 1 p * resonance to be sensitive to the nature of the intermolecular bonding at the para -carboxylic acid group, and a shift to low energy for a - 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 s * 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.
- Published
- 2016
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