Time-resolved spectroscopy of the singlet excited state of betanin in aqueous and alcoholic solutions
| Autor: | Sławomir Wybraniec, Dorota Prukała, Marek Sikorski, Monika Wendel, Stanislaw Nizinski, Karolina Starzak, Dominika Szot, Dorota Tuwalska, Gotard Burdzinski |
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| Rok vydání: | 2015 |
| Předmět: |
Ethylene Glycol
Methanol General Physics and Astronomy Quantum yield Water Photochemistry Solutions chemistry.chemical_compound Intersystem crossing Spectrometry Fluorescence chemistry Excited state Ultrafast laser spectroscopy Quantum Theory Singlet state Betacyanins Physical and Theoretical Chemistry Time-resolved spectroscopy Ground state Betanin |
| Zdroj: | Physical Chemistry Chemical Physics |
| ISSN: | 1463-9084 |
| Popis: | The photophysical properties of betanin in aqueous and alcoholic solutions were determined at room temperature using ultrafast UV-vis-NIR transient absorption spectroscopy (λexc = 535 nm). Its S1 → Sn (n > 1) absorption bands appear with maxima at about λ ∼ 450 and 1220 nm. The short betanin S1 state lifetime (6.4 ps in water) is mainly determined by the efficient S1 → S0 radiationless relaxation, probably requiring a strong change in geometry, since the S1 lifetime grows to 27 ps in the more viscous ethylene glycol. The fluorescence quantum yield is very low (Φf ∼ 0.0007 in water), therefore this deactivation path is of minor importance. Other processes, such as S1 → T1 intersystem crossing or photoproduct formation, are virtually absent, since full S0 ← S1 ground state recovery is observed within tens of picoseconds after photoexcitation. The observed fast light-to-heat conversion in the absence of triplet excited state formation supports the idea that betanin is a photoprotector in vivo. |
| Databáze: | OpenAIRE |
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