"Ultrafast Dynamics and Temperature Effects on the Quantum Efficiency of the Ring-Opening Reaction of a Photochromic Indolylfulgide
"T. Brust, S. Draxler, S. Malkmus, C. Schulz, M. Zastrow, K. Rück-Braun, W. Zinth und M. Braun
Journal of Molecular Liquids 141 (2008) 137-139
The ultrafast ring-opening reaction of the molecular switch 1,2-Dimethyl-3-indolylfulgide dissolved in acetonitrile is investigated by temperature dependent quantum efficiency measurements and timeresolved transient absorption spectroscopy in the ultraviolet and visible spectral range. The photoreaction is found to be thermally activated with an activation energy of about 1640 cm-1. The transient absorption signal is bi-exponential with the time constants τ1 = 0.7 ps and τ2 = 12 ps. The fast time constant is due to solvation dynamics, while the main component τ2 is attributed to the excited state lifetime and product formation. A long-lived intermediate state in the photoreaction can be excluded.
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Generation of light pulses on the time scale of 5 fs