Excited-State Intramolecular Proton Transfer in 10-Hydroxybenzo[h]quinoline
| Autor: | Pi-Tai Chou, Yi-Ming Cheng, Wei-Shan Yu, Youn-Chan Chen, Yi-Hsuan Chou, and Ching-Yen Wei |
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| Rok vydání: | 2001 |
| Předmět: | |
| Zdroj: | The Journal of Physical Chemistry A. 105:1731-1740 |
| ISSN: | 1520-5215 1089-5639 |
| Popis: | The dynamics of excited-state intramolecular enol−keto proton-transfer tautomerism in 10-hydroxybenzoquinoline (HBQ) and its deuterated analogue (DBQ) have been investigated by steady-state absorption and fluorescence spectroscopy, femtosecond fluorescence upconversion in combination with pump−probe transient absorption experiments in nonpolar solvents. In cyclohexane, the time scale for both proton and deuterium transfer in the excited state cannot be resolved under the response limit of ca. 160 and 200 fs, respectively, of our current upconversion and transient absorption systems. The initially prepared keto tautomer is in a higher lying excited state, possibly the state (prime indicates the keto-tautomer form) which then undergoes a ∼330 fs → internal conversion, resulting in a highly vibrationally excited state. Subsequently, a solvent-induced vibrational relaxation takes place in a time scale of 8−10 ps followed by a relatively much longer, thermally cooled → decay rate of 3.3 × 109 s-1 (τf ∼ 300 ps-... |
| Databáze: | OpenAIRE |
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