engleski

Electron spin relaxation in solid ethanol: the effect of matrix disorder

Coupling of the electron spin to disorder modes of various doped matrices has been extensively studied due to the sensitivity of the approach toward dynamical properties of the observed systems. Amorphous solids in comparison with crystals exhibit anomalous dynamics at low temperatures [1, 2]. In this context the application of pulsed electron paramagnetic resonance (EPR) spectroscopy offers the advantage of studying local properties in the vicinity of paramagnetic center. Since solid ethanol can be prepared in phases characterized by different types of disorder [3], we have used it as a convenient model system for studying low-molecular weight solids by EPR [4]. Here we present electron spin-lattice relaxation data of TEMPO paramagnetic molecule incorporated in crystalline and glassy state of solid ethanol in the temperature interval well below the ethanol glass transition. The largest difference between the data can be detected at temperatures below 10 K and related to the presence of excess of low-energy excitations in glasses that are not present in crystals. These findings will be correlated with conclusions derived from nuclear magnetic resonance spectroscopy [5]. References [1] C. Talón, M. A. Ramos, S. Vieira, G. J. Cuello, F. J. Bermejo, A. Criado, M. L. Senent, S. M. Bennington, H. E. Fischer, and H. Schober, Phys. Rev. B 58, 745 (1998). [2] D. A. Parshin, H. R. Schober, and V. L. Gurevich, Phys. Rev. B 76, 064206 (2007). [3] M. A. Ramos, V. Rodríguez-Mora, and R. J. Jiménez-Riobóo, J. Phys.: Condens. Matter 19, 205135 (2007). [4] M. Kveder, D. Merunka, M. Jokić, J. Makarević, and B. Rakvin, Phys. Rev. B 80, 052201 (2009). [5] T. Eguchi, G. Soda, and H. Chihara, Mol. Phys. 40, 681 (1980).

matirx disorder; EPR; glassy state

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