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Picosecond Studies of Structure and Dynamics of Electronically Excited Molecules in Solution

Year: 1985
Type: dissertation
Abstract: Picosecond spectroscopy was used to probe the liquid phase dynamics of two different chemical systems.In the first study, the rotational reorientation times of rhodamine 6G (R6G) and p-terphenyl (PTP) were measured as a function of solvent viscosity.The viscosity was varied either by changing the solvent or by changing the pressure 1 in a single solvent.The differences between the two molecules PTP and R6G provided a means of evaluating the role of solute structure and solute-solvent interactions on the dynamics on rotational reorient ation.For example, the rotational behavior of PTP was well described by simple hydrodynamic models as embodied in the Stokes-Einstein-Debye equation.In contrast, the rotational reorientation dynamics of the charged molecule R6G were not well described by these models.High pressure () 6 kbar) techniques were developed for this study to provide a means of varying the viscosity of a single solvent.The new infQrmation from these experiments demonstrated that dielectric friction plays an important role in governing the rotational motion of charged solute molecules in polar solvents.Models incorporating the role of dielectric friction accurately predicted the observed experimental trends.The validity of this dielectric friction model was comfirmed in studies of the effect of added salt on rotational reorientation dynamics.The dielectric friction model also adds new insight into the role of hydrogen bonded complexes in rotational behavior.In particular, I would like to thank Fred Wolfe for patiently evaluating many designs to optimize the performance of many pieces of apparatus.Helpful scientific discussions took place which provided insights at crucial stages of this work.For this help I would like to thank
Language: English
Field: Chemistry
Open Access status: green
OpenAlex ID: W2778142858
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