Ultrafast Ring-Closure Reaction of Photochromic Indolylfulgimides Studied with UV-Pump-IR-Probe Spectroscopy

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• 作者：Florian O. Koller ; Wolfgang J. Schreier ; Tobias E. Schrader ; Stephan Malkmus ; Christine Schulz ; Steffen Dietrich ; Karola R&uuml ; ck-Braun ; Markus Braun
• 刊名：Journal of Physical Chemistry A
• 出版年：2008
• 出版时间：January 17, 2008
• 年：2008
• 卷：112
• 期：2
• 页码：210 - 214
• 全文大小：207K
• 年卷期：v.112,no.2(January 17, 2008)
• ISSN：1520-5215

文摘

The ring-opening and ring-closure reactions of a photochromic indolylfulgimide are investigated withfemtosecond vibrational spectroscopy. Spectral signatures due to excited-state decay and vibrational coolingare seen in the mid-IR region. For the ring-opening reaction triggered with visible pulses, a lifetime of theexcited electronic state of 4 ps was obtained in polar solution. In a nonpolar solvent, this time constant isreduced to 2 ps. The ring-closure reaction induced with UV pulses displays an excited-state lifetime and thusa building of the photoproduct of roughly 0.5 ps. For all processes, the subsequent cooling occurs on a 15-pstime scale lasting up to ~50 ps. The time-resolved IR measurements do not support the existence of anylong-living intermediate states.