Dipartimento di Chimica, Ingegneria Chimica e Materiali, Università di L'Aquila, via Vetoio (Coppito 1), 67010 L'Aquila, Italy.
J Phys Chem B. 2010 Feb 11;114(5):1915-24. doi: 10.1021/jp909465f.
Quantitative characterization of quantum states in complex molecular systems is a rather complicated task because of the necessity of maintaining the pure quantum definition of a state interacting with a configurationally complex molecular environment. Unfortunately, many of the "observables" that are of interest for a chemist, typically dealing with "complex objects", belong to the above class and their theoretical modeling may represent a hard task. In this respect, we have developed a new theoretical methodology, "perturbed matrix method", essentially based on the perturbation theory whose main aim is the characterization of the quantum states of a predefined portion of a complex molecular system, e.g., a solute, classically interacting with the environment, e.g., the solvent. This method has been used in this study to systematically characterize, for the first time and in conjunction with experimental observations, the intrinsic nature of pyrene whose vibrational and electronic states are highly sensitive to the nature of molecular environment. More precisely, pyrene shows a strong alteration of spectral intensities upon modification of polarity of the solvent. This property has been extensively used in many experimental studies and has been interpreted in the present study by characterizing pyrene electronic states as fluctuating states strictly connected to the polarity and the fluctuations of the surrounding medium. A correct theoretical modeling has been also obtained and commented for the vertical transitions in different media and also for the vibronic structure for the first transition in water.
对复杂分子体系中量子态进行定量描述是一项相当复杂的任务，因为需要保持与构象复杂的分子环境相互作用的态的纯量子定义。不幸的是，对于化学家来说，许多“可观测物”通常属于上述类别，它们属于化学家感兴趣的“复杂对象”，并且它们的理论建模可能代表一项艰巨的任务。在这方面，我们开发了一种新的理论方法，即“微扰矩阵法”，该方法主要基于微扰理论，其主要目的是对复杂分子体系的预定部分（例如，与环境经典相互作用的溶质）的量子态进行特征化，例如溶剂。本研究首次使用该方法结合实验观测，系统地对芘的内在性质进行了特征化，芘的振动和电子态对分子环境的性质非常敏感。更确切地说，芘的光谱强度在溶剂极性发生变化时会发生强烈的变化。这种性质已在许多实验研究中得到广泛应用，并在本研究中通过将芘电子态描述为与极性和周围介质的波动严格相关的波动态来进行解释。我们还获得并评论了不同介质中垂直跃迁以及水中第一跃迁的振动态结构的正确理论模型。
