Electron spin-lattice relaxation in solid ethanol: the effect of nitroxyl radical hydrogen bonding and matrix disorder

TL;DR

This study investigates how hydrogen bonding and matrix disorder influence electron spin-lattice relaxation in solid ethanol, revealing different relaxation mechanisms in crystalline versus glassy states.

Contribution

It provides new insights into the effects of hydrogen bonding and matrix disorder on spin relaxation mechanisms in ethanol matrices.

Findings

Hydrogen bonding significantly affects relaxation in glassy ethanol.

Different relaxation mechanisms dominate in crystalline and glassy ethanol.

Vibrational modes and Raman processes influence relaxation at higher temperatures.

Abstract

The electron spin-lattice relaxation of TEMPO and TEMPONE was measured at temperatures between 5 and 80 K in crystalline and glassy ethanol using X-band electron paramagnetic resonance spectroscopy. The experimental data at the lowest temperatures studied were explained in terms of electron-nuclear dipolar interaction between the paramagnetic center and the localized excitations, whereas at higher temperatures low-frequency vibrational modes from the host matrix and Raman processes should be considered. The strong impact of hydrogen bonding between the dopant molecule and ethanol host on the spin relaxation was observed in ethanol glass whereas in crystalline ethanol both paramagnetic guest molecules behaved similarly.