EPR spectroscopy of solid trehalose: the effect of matrix disorder on the dynamics of the paramagnetic centers

Šarić, Iva (2014) EPR spectroscopy of solid trehalose: the effect of matrix disorder on the dynamics of the paramagnetic centers. Doctoral thesis, Faculty of Science > Department of Physics.

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Abstract

In the multidisciplinary quest for understanding of glasses, the study of molecular glasses provides an adequate experimental framework to investigate dynamics in states characterized by frozen-in disorder. Due to the fact that trehalose, a glass-forming disaccharide found in nature, exhibits the highest glass transition temperature, T_g, and the best-developed boson peak of saccharides, it is interesting to be studied in the context of low-temperature anomalies of glasses related to the impact of hydrogen-bonded network. Here, a comparative study of trehalose glassy and anhydrous polycrystalline form, trehalose-β, using pulsed X-band electron paramagnetic resonance (EPR) spectroscopy is presented. The radiation-induced paramagnetic centers are used to study the coupling of the electron spin with the lattice as a function of the frozen-in disorder. The effective spin lattice relaxation time is presented in the large temperature interval, from 0,012 T_g to 0,7 T_g, indicating more effective energy exchange between the spin system and the lattice for the paramagnetic defects in the glassy than trehalose-β crystalline state. The theoretical analysis of the experimental data is put into the framework of the contribution of the disorder modes. Furthermore, understanding the behavior of radiation-induced defects in trehalose in different polymorphic forms is important for radiation dosimetry purposes and for the detection and characterization of irradiated final products in the pharmaceutical and food industry. Therefore, EPR signals in gamma irradiated trehalose in different polymorphic forms were studied with dosimetry applications in view.

Item Type: Thesis (Doctoral thesis)
Keywords: trehalose ; glassy state ; paramagnetic centers ; pulse EPR ; spin-lattice relaxation
Supervisor: Ilakovac Kveder, Marina
Date: 27 February 2014
Number of Pages: 105
Subjects: NATURAL SCIENCES > Physics
Divisions: Faculty of Science > Department of Physics
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 19 Mar 2014 13:31
Last Modified: 19 Mar 2014 13:31
URI: http://digre.pmf.unizg.hr/id/eprint/652

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