Lifetime of the impurity-induced fluorescence and zero-phonon line emission in a biphenyl crystal

Fluorescence spectrum and its lifetime in a biphenyl single crystal were measured by a picosecond UV laser pulse. It was found that in addition to an impurity induced broad band fluorescence, a zero-phonon line appears at 533 nm if the excitation energy is larger than the band gap energy, in a single crystal of biphenyl. In contrast to a temperature insensitive lifetime of the zero-phonon emission, the broad band fluorescence was shown to have a shortest lifetime at T1 reflecting the divergence of the fluctuation of atomic displacement near the phase transition at 40 K.

Keywords:

• Biphenyl
• fluorescence
• zerophonon
• phase transition
• fluctuation