The present work discusses the IR spectroscopic experiments and
quantum-chemical DFT study of structure and intermolecular binding in the
intermediate gas-liquid systems of aromatics, namely, benzene, furane,
pyridine and thiophene. These systems can be generated in thin layers near a
solid surface by two different methods, depending on the physical properties
of the sample. The first method includes evaporation with a subsequent
compression of a sample in a variable thickness optical cell is applied to
volatile components: benzene, furane, thiophene. For benzene and pyridine,
the second method is used, which involves a heating-initiated evaporation
into a closed inter-window space with an after-cooling of a sample. It was
shown that the formed layer is not an adsorbate or a condensate. The IR data
obtained by these two methods allow to conclude that the revealed systems of
the considered aromatics manifest dual gas-liquid spectral properties which
can pass into each other in case of varying external conditions. According
to the DFT calculation results, the spatial arrangement in the aromatic thin
layers can be described as a combination of ?- and ?- bonded clusters, which
simulate the gas and the liquid phase state properties.