Nonradiative decay dynamics of methyl-4-hydroxycinnamate and its hydrated complex revealed by picosecond pump-probe spectroscopy
Abstract
The lifetimes of methyl 4-hydroxycinnamate (OMpCA) and its mono-hydrated complex (OMpCA-H2O) in the S1 state have been measured by picosecond pump-probe spectroscopy in a supersonic beam. For OMpCA, the lifetime of the S1 - S0 origin is 8 – 9 ps. On the other hand, the lifetime of OMpCA-H2O complex at the origin is 930 ps, which is ~100 times longer than that. Furthermore, in the complex the S1 lifetime shows rapid decrease at an energy of ~200 cm-1 above the origin and finally becomes as short as 9 ps at ~500 cm-1. Theoretical calculations with symmetry-adapted cluster-configuration interaction (SAC-CI) method suggest that the observed lifetime behavior of the two species is described by noradiative decay dynamics involving trans →cis isomerization. That is both OMpCA and OMpCA-H2O in the S1 sate decay due to the trans→cis isomerization, and the large difference of the lifetimes between them is due to the difference of the isomerization potential energy curve. In OMpCA, the trans → cis isomerization occurs smoothly without a barrier on the S1 surface, while in OMpCA-H2O complex, there exists a barrier along the isomerization coordinate. The calculated barrier height of OMpCA-H2O is in good agreement with that observed experimentally.
Journal
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- Physical Chemistry Chemical Physics
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Physical Chemistry Chemical Physics 14 (25), 8999-9005, 2012-03-13
Royal Society of Chemistry
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Details 詳細情報について
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- CRID
- 1050577740962068736
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- NII Article ID
- 120005615676
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- Text Lang
- en
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- Article Type
- journal article
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- Data Source
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- IRDB
- CiNii Articles