Date of Award
Doctor of Philosophy
Presented in this dissertation are the experimental and theoretical results of hole burning properties of aluminum phthalocyanine tetrasulphonate in several different matrices: (i) hyperquenched glassy water; (ii) cubic ice; and (iii) water confined into poly(2-hydroxyethylmethacrylate) (poly-HEMA). In addition, results of photochemical hole burning studies obtained for phthalocyanine tetrasulphonate in HGW and free base phthalocyanine in ortho-dichlorobenzene glass are reported. The studies provide further evidence supporting the NPHB mechanism and to provide more insight that leads to a better understanding of the kinetic events (dynamics) in glasses, and various dynamical processes of different fluorescent chromorphores in various amorphous solids. The following issues are addressed in detail: (1) time evolution of hole being burned under different conditions and in different hole burning systems; (2) temperature dependent hole profile; and (3) the structure/dynamics of water in confined space, which has been studied, in part because of the importance of non-freezable water in biological systems.;Finally, the nature of water above its glass transition temperature ( Tg) using polarization-resolved single molecule spectroscopy is addressed. A single Rhodamine 700molecule is also studied in supercooled liquid ethanol matrix. It shows that single Rh700 molecule starts to rotate only ~2 K above Tg of ethnol. In contrast, no rotation of Rh700 is observed in the water in the temperature range from 110 to 170 K. This result provides strong evidence that the nature of water above T = 136 K (i.e. a widely stated value for Tg of hyperquenched water and vapor deposited glassy water) is not a fragile liquid.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Nhan Chuong Dang
Dang, Nhan Chuong, "Probing properties of glassy water and other liquids with site selective spectroscopies " (2005). Retrospective Theses and Dissertations. 1858.