Institute of Applied Radiation Chemistry, Laboratory of Laser Molecular Spectroscopy, Technical University of Lodz, Wroblewskiego 15, 93-590 Lodz, Poland.
J Phys Chem A. 2012 Apr 26;116(16):4000-9. doi: 10.1021/jp3017979. Epub 2012 Apr 12.
A promising material in medicine, electronics, optoelectronics, electrochemistry, catalysis, and photophysics, tetrasulphonated aluminum phthalocyanine (AlPcS(4)), is investigated by means of steady-state and time-resolved pump-probe spectroscopies. Absorption and steady-state fluorescence spectroscopy indicate that AlPcS(4) is essentially monomeric. Spectrally resolved pump-probe data are recorded on time scales ranging from femtoseconds to nanoseconds. The nature of these fast processes and pathways of the competing relaxation processes from the initially excited electronic states in aqueous and organic (dimethyl sulfoxide) solutions are discussed. The decays and bleaching recovery have been fitted in the ultrafast window (0-10 ps) and later time window extending to nanoseconds (0-1 ns). While the excited-state dynamics have been found to be sensitive to the solvent environment, we were able to show that the fast dynamics is described by three time constants in the ranges of 115-500 fs, 2-25 ps, and 150-500 ps. We were able to ascribe these three time constants to different processes. The shortest time constants have been assigned to vibrational wavepacket dynamics. The few picosecond components have been assigned to vibrational relaxation in the excited electronic states. Finally, the 150-500 ps components represent the decay from S(1) to the ground state. The experimental and theoretical treatment proposed in this paper provides a basis for a substantial revision of the commonly accepted interpretation of the Soret transition (B transition) that exists in the literature.
四磺化铝酞菁（AlPcS(4)）是一种在医学、电子学、光电子学、电化学、催化和光物理等领域有应用前景的材料，本研究采用稳态和时间分辨泵浦探测光谱法对其进行了研究。吸收和稳态荧光光谱表明，AlPcS(4)基本上是单体的。在飞秒到纳秒的时间范围内记录了光谱分辨的泵浦探测数据。讨论了这些快速过程的性质和在水溶液和有机（二甲基亚砜）溶液中从最初激发的电子态的竞争弛豫过程的途径。在超快窗口（0-10 ps）和稍后的扩展到纳秒的时间窗口（0-1 ns）中拟合了衰减和漂白恢复。虽然激发态动力学对溶剂环境敏感，但我们能够表明，快速动力学由三个时间常数描述，范围为 115-500 fs、2-25 ps 和 150-500 ps。我们能够将这三个时间常数归因于不同的过程。最短的时间常数被分配给振动波包动力学。少数皮秒分量被分配给激发电子态中的振动弛豫。最后，150-500 ps 分量代表从 S(1)到基态的衰减。本文提出的实验和理论处理为对文献中普遍存在的 Soret 跃迁（B 跃迁）的解释进行实质性修正提供了基础。
