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A picosecond transient absorption study of the intramolecular excited state proton transfer in 3-hydroxyflavone: assignment of the observed bands |
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| Affiliation: | 1. Key Laboratory of Photochemical Conversion and Optoelectronic Materials and CityU–CAS Joint Laboratory of Functional Materials and Devices, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China;2. University of Chinese Academy of Sciences, Beijing 100049, China;3. School of Chemistry and Chemical Engineering, Suzhou University, Suzhou 234000, China |
| Abstract: | The time-resolved transient absorption and gain of 3-hydroxyflavone in ethanol ( T = 300 and 173 K) and MCH ( T = 300 and 198 K) has been investigated. Two absorption bands (A and B) and two gain bands (E1 and E2) have been observed. Band A (lying in the 5200 Å spectral region) appears during and just after the excitation step and is assigned to the normal excited form Nx Band B (lying in the 6050 Å spectral region) appears after band A and is assigned to the tautomer form T. A gain band E2 (lying at λ=5400 Å) appears at the same time as the B band and is attributed to the T→T emission. A gain band E1 (lying at λ = 5730 Å) appears earlier than the E2 band. Its origin is discussed and two possible assignments are presented: vibronic progression of the emission spectrum of T or formation of an intermediate species on the proton transfer pathway from Nx to T. |
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