| Popis: |
Cis-stilbene was excited by one photon at 270 nm in the gas phase and then probed by ionization at infrared wavelengths (810 and 2100 nm), recording the delay-time dependent mass spectra. We found not only a decay of 300 fs, previously assigned to departure from the fluorescent region, but also a second time constant (160 A), probably representing departure from the 'perpendicular minimum' (excited state with twisted ethene part). In addition, two coherent oscillations (periods 140 and approximate to600 fs) were found in the 300-fs window. We discuss their implications for the initial motion and point out the importance of vibronic interaction of excited states. (C) 2004 Elsevier B.V. All rights reserved. Chemical Physics Letters |
