Encapsulated Atomic Hydrogen in Octamethyl-POSS Cages: A Pulsed EPR Study

Abstract

Encapsulated atomic hydrogen in polyhedral oligomeric silsesquioxane (POSS) cages is a promising candidate for spin-based quantum technologies. Key parameters such as spin relaxation times and magnetic interactions with surrounding electron and nuclear spins can be typically probed with advanced electron paramagnetic resonance (EPR) methods. Here we present a detailed pulsed EPR study of the species H@Si8O12R8 with R=CH3, namely encapsulated atomic hydrogen in the octamethyl POSS derivative. The temperature dependence of the spin-lattice relaxation rate 1/ (Formula presented.) is analyzed in terms of a Raman process with a Debye temperature of (Formula presented.) K and a thermally activated process with (Formula presented.) (552 cm−1), whereas, the phase memory time (Formula presented.) shows the typical shortening behaviour at (Formula presented.) K observed for all methyl-containing derivatives. The hyperfine coupling of the cage (Formula presented.) Si nuclei is measured by hyperfine sublevel correlation (HYSCORE) spectroscopy and is found to fulfil the so-called “matching condition” at the low-field EPR transition. The potential of this paramagnetic molecule to perform one-qubit quantum operations is probed by room-temperature Rabi oscillations.