SPECTROSCOPIC STUDY OF THE PICOSECOND PHOTOISOMERIZATION OF STILBENE

New aspects of the photoisomerization dynamics of ethylenic double bonded systems are elucidated via picosecond time-resolved experiments on trans- and cis-stilbene in room temperature hexane solution.For trans, but not cis, a transient spectrum peaked at 585 nm was generated immediately after excitation by a 265 nm pulse. The spectrum narrowed over the first 25 ps and its integral decayed exponentially, τ = 90± 5 ps. The former decay is interpreted as relaxation of the optically generated vibrational energy excess; the latter as the decay time of trans (1B) into twisted forms. © 1979.