Modulation spectroscopy of highly excited states in organic crystals

Electro- and magneto-modulation technique is developed and applied to the spectroscopy in the synchrotron radiation region. The highly excited molecular states undergo various competitive and sequential radiationless transition to lower energy states until relatively stable species (the lowest singlet exciton S1) are formed. In condensed matters a specific intermolecular energy conversion phenomenon, so called exciton fission process appears significant. In addition, dissociation of highly excited state into charged carriers is also an important process. In order to investigate these processes, the authors applied the external field modulation technique on the fluorescence excitation spectra of typical organic crystals; anthracene and p-terphenil