Solvation of charge in aromatic/noble gas Van der Waals clusters

The results of an experimental study of the ionisation threshold in the various structural isomers of the Van der Waals clusters aniline-(argon)n (n = 1−5) and 4-fluorostyrene-(argon)n (n = 1–2) using resonant two-photon ionisation are reported. The data validate and generalise the site-specific modified shift additivity rule. They show an interesting influence of the localisation of argon atoms at the surface of the chromophore on the value of the net shift of the ionisation potential. Interpreatation of the results involves evaluation and balancing between the charge-induced-dipole interaction and dispersion interaction.