Surface Propensity of Anions in a Binary Ionic-Liquid Mixture Assessed by Full-Range Angle-Resolved X-ray Photoelectron Spectroscopy and Surface-Tension Measurements

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Oz E., Sahin O., Okur H. I., Suzer S.

CHEMPHYSCHEM, cilt.21, sa.21, ss.2397-2401, 2020 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 21 Sayı: 21
  • Basım Tarihi: 2020
  • Doi Numarası: 10.1002/cphc.202000750
  • Dergi Adı: CHEMPHYSCHEM
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, PASCAL, Biotechnology Research Abstracts, Chimica, Compendex, EMBASE, INSPEC, MEDLINE
  • Sayfa Sayıları: ss.2397-2401
  • Anahtar Kelimeler: angle-resolved XPS, attenuation model, ionic liquid mixtures, surface enrichment, surface tension, OUTER ATOMIC SURFACE, ELECTRONIC ENVIRONMENT, WATER, INTERFACE
  • Atatürk Üniversitesi Adresli: Hayır

Özet

Angle-resolved X-ray photoelectron spectroscopy and contact-angle measurements guided by a signal attenuation model are utilized to extract molar composition and anion enrichment in the vacuum interface of a binary ionic liquid mixture, having a common quaternary ammonium cation and two different anions. By using the intensity ratio of the F1s peaks belonging to the two different anions recorded at the full electron take-off angle range, from 0 degrees to 80 degrees, we have determined that only a fractionally covered and anion enriched surface layer can predict the AR-XPS data, which is also consistent with surface tension measurements. Moreover, the more bulky and non-spherical anion enrichment is evident even at the conventional and the so assumed bulk sensitive take-off angle of 0 degrees. This methodology provides a surface enrichment factor of the molecular ions and clearly serves as an experimental evidence for recently debated surface layering and/or island structure in ionic liquid systems.