Jet spectroscopy of anthracene-alkane complexes

The fluorescence excitation spectra are reported for complexes of anthracene with n-alkanes. The spectra have only weak low-frequency mode structure, which indicates that the complexation geometries are stable with respect to excitation of the anthracene host. At the 2:1 complexation level, the spectra indicate that the complexation geometry changes over from trans, which is favoured for short alkanes, to the cis form for alkanes longer than heptane. This behaviour is attributed to increased guest-guest interaction, which favours the formation of alkane dimers on the anthracene surface.