Naslov
Effect of glassy modes on spin-lattice relaxation of TEMPO radical in ethanol

Autori
Merunka, Dalibor ; Kveder, Marina ; Jokić, Milan ; Rakvin, Boris ;

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
EUROMAR 2012 Magnetic Resonance Conference / - Dublin, 2012, 206-206

Skup
EUROMAR 2012

Mjesto i datum
Dublin, Irska, 01.07.2012. - 05.07.2012

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
electron spin-lattice relaxation; dynamics of glasses

Sažetak
Spin-lattice relaxation (SLR) of TEMPO radical in the glassy (G) and crystalline (C) ethanol was measured by X-band EPR technique between 5 and 80 K. The SLR rates Gamma=1/T1 are higher in G- ethanol than in C-ethanol for both protonated and deuterated samples, while the excess SLR rate in G-ethanol DGamma=Gamma(G)−Gamma(C) is much higher for the protonated sample (Fig. 1). The results indicate that DGamma is produced by extra modes existing in glassy matrix, which are coupled to the electron spin of radical by the electron- nuclear dipolar (END) interaction. Using the soft- potential model for glassy modes and assuming END interaction between the electron spin and matrix protons, the expressions for SLR rates due to various mechanisms of glassy modes was derived. The SLR rates were evaluated for protonated G- ethanol from reported experimental data. The results indicate two effective mechanisms: thermally activated relaxation of double-well systems (DWS) and phonon-induced relaxation of quasi-harmonic local modes (QLM). The SLR rate induced by these mechanisms correlates well with the experimental DGammain both the order of magnitude and the temperature dependence (Fig. 1).

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Kemija

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