Replacing all protons on a polymer by deuterium has a dramatic impact on spin-dependent properties of the material in devices.

We report a measurement of the dimensionless enhancement factor κ 0 for the Xe pair commonly used in spin exchange optical pumping (SEOP) to produce hyperpolarized 129 Xe. κ 0 characterizes the amplification of the 129 Xe magnetization contribution to the Rb electronic effective field, compared to the case of a uniform continuous medium in classical magnetostatics. The measurement is carried out in Rb vapor cells containing both 3 He and 129 Xe and relies on the previously measured value of κ 0 for the Rb-3 He pair. The measurement is based on (1) the optically detected (Faraday rotation) frequency shift of the 87 Rb EPR hyperfine spectrum caused by the SEOP nuclear polarization and subsequent sudden destruction of nuclear polarization of both species and (2) a comparison of NMR signals for the two species acquired just prior to the EPR frequency shift measurements. We find (κ 0 ) RbXe = 518 ± 8, in good agreement with previous measurements and theoretical estimates but with improved precision. *

Electron and hole spins in organic light-emitting diodes constitute prototypical two-level systems for the exploration of the ultrastrong-drive regime of light-matter interactions. Floquet solutions to the time-dependent Hamiltonian of pairs of electron and hole spins reveal that, under non-perturbative resonant drive, when spin-Rabi frequencies become comparable to the Larmor frequencies, hybrid light-matter states emerge that enable dipole-forbidden multi-quantum transitions at integer and fractional g-factors. To probe these phenomena experimentally, we develop an electrically detected magnetic-resonance experiment supporting oscillating driving fields comparable in amplitude to the static field defining the Zeeman splitting; and an organic semiconductor characterized by minimal local hyperfine fields allowing the non-perturbative light-matter interactions to be resolved. The experimental confirmation of the predicted Floquet states under strong-drive conditions demonstrates the presence of hybrid light-matter spin excitations at room temperature. These dressed states are insensitive to power broadening, display Bloch-Siegert-like shifts, and are suggestive of long spin coherence times, implying potential applicability for quantum sensing.