Picosecond Transient Raman Spectra of S₁ Bis(Methylstyryl)- Benzene: Observation of S₁←SnResonance Emission

Abstract

We have been studying the excited state spectra of several molecules related to electroluminescent conducting polymers. The excited state structure corresponds to the conducting state in these systems. We have obtained data on 1,4-bis(2,2′-methylstyryl)- benzene (2MSB) as a model system of poly (P-phenylenevinylene) (PPV). We observe both sharp and broad features in the spectra. The sharp bands occur at a constant energy shift relative to the probe wavelength. We attribute the sharp bands to resonance Raman bands of the S₁ state of 2MSB. We assign the broad band at ∼740 nm to resonance emission between Sn and S₁. We believe that this is the first observation of resonance secondary radiation (RSR) between two electronically excited states in a large molecule.