Knowledge Bank

Rotationally resolved fluorescence excitation spectra of the $S1(1Lb)\leftarrow S0$ origin bands of 7-azaindole and its Argon complex have been recorded and analyzed. The derived rotational parameters give information about the geometries of the two molecules in both electronic states. The Argon atom moves when the UV photon is absorbed because there are significant differences in the $S0$ and $S1$ intermolecular potential energy surfaces. A large rotation of $S1\leftarrow S0$ electronic transition moment of 7-azaindole relative to that of indole gives further information about this solvent reorganization.