Origins of the differences in solvation by alkanes and perfluoroalkanes. Evidence from the S2-S0 spectra of jet-cooled van der Waals complexes of xanthione and azulene

H. K. Sinha, O. K. Abou-Zied, M. Ludwiczak, A. Maciejewski, R. P. Steer

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The S2-S0 fluorescence excitation spectra ofxanthione (XT) and azulene (AZ) complexed with 1 or 2 molecules of the C1 to C10 n-alkanes and the C1 to C6 perfluoro-n-alkanes have been measured. The 1:1 complexes exhibit microscopic solvent shifts, Δ \ ̄gn, which are larger for the alkanes than the corresponding perfluoroalkanes, despite the larger molecular polarizability of the latter. The values of Δ \ ̄gn increase monotonically with carbon number of the adduct to C10 in 1:1 n-alkane complexes with XT and to C5 in 1:1 n-alkane complexes with AZ. However, Δ \ ̄gn exhibits no further increase beyond C2 in 1:1 perfluoro-n-alkane complexes with XT and beyond C3 in 1:1 perfluoro-n-alkane complexes with AZ. The results are interpreted in terms of a model in which the n-alkanes stretch out along the long axis of the chromophore and 'wet' its surface whereas the perfluoro-n-alkanes with carbon numbers ≥ 3 away from the surface of the chromophore and are 'non-wetting'.

Original languageEnglish
Pages (from-to)547-554
Number of pages8
JournalChemical Physics Letters
Issue number6
Publication statusPublished - Dec 9 1994


ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Spectroscopy
  • Condensed Matter Physics
  • Atomic and Molecular Physics, and Optics
  • Surfaces and Interfaces

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