Ultrafast Molecular Relaxation of Isolated Stllbene: Measurements by Picosecond Pump-Probe Techniques

In this Letter, we report measurements of the picosecond relaxation time of trans-stilbene in S1 under collisionless conditions. By acurate determination of the zero-time in our picosecond pump-probe experiments we obtained r = 3 ± 0.5 ps, which is entirely consistent with our earlier measurements of IVR rates of stilbene in bulbs and beams. This establishes the molecular nature of the decay in these picosecond pump-probe multiphoton ionization (or mass spectrometry) experiments