研究目的
To investigate the ultrafast charge transfer and intersystem crossing processes of 9-anthraldehyde in ethanol and hexane solvents using femtosecond transient absorption spectroscopy and quantum chemical calculations.
研究成果
The study successfully elucidated the ultrafast intramolecular charge transfer and intersystem crossing dynamics in 9-anthraldehyde. Charge transfer occurs within 0.11 ps in ethanol and 0.23 ps in hexane, faster in more polar solvents. Intersystem crossing to triplet states occurs with time constants of 22.3 ps in ethanol and 21.4 ps in hexane, with similar rates due to small energy differences between S1 and triplet states. These processes are significant for understanding phototoxicity in anthraldehyde-based drugs.
研究不足
The lifetime of the triplet states could not be precisely measured as it is beyond the time resolution of the system (nanosecond scale not fully resolved). The study is limited to two solvents (ethanol and hexane), and the mechanisms might vary in other environments. The quantum chemical calculations rely on specific functionals and basis sets, which may have approximations.
1：Experimental Design and Method Selection:
The study employed femtosecond transient absorption spectroscopy to monitor the temporal evolution of photoexcited 9-anthraldehyde, combined with quantum chemical calculations using TD-DFT B3LYP/6-311+G(d,p) to optimize geometries and calculate excited state energies and properties.
2：Sample Selection and Data Sources:
9-anthraldehyde (99% purity) from Aladdin was dissolved in ethanol and hexane solvents at a concentration of 1 mM. Static UV-VIS absorption spectra were recorded using a UV-vis spectrometer.
3：List of Experimental Equipment and Materials:
Equipment includes a femtosecond laser system (Ti:sapphire oscillator and regenerative amplifier), BBO crystal for second harmonic generation, CaF2 for white continuum generation, flow cell with quartz windows, CCD camera (PI-MAX), spectrometer (Princeton Instruments SpectraPro 2500i), and Gaussian09W software for calculations. Materials include 9-anthraldehyde, ethanol, hexane, and quartz cells.
4：Experimental Procedures and Operational Workflow:
The sample was excited at 400 nm, and transient absorption spectra were measured from 420 to 680 nm with delay times up to 1 ns. The polarization angle was set at the magic angle, and data were collected with a precision linear stage. Quantum calculations involved geometry optimization and energy calculations in solvents using SCRF.
5：Data Analysis Methods:
Data were fitted with multi-exponential functions and analyzed using singular value decomposition (SVD) and global fit analysis to extract time constants and decay-associated difference spectra.
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