2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/156766We measure magnetization changes in a single crystal of the single-molecule magnet Fe8 when exposed to intense, short (<20 $μ$s) pulses of microwave radiation resonant with the m = 10 to 9 transition. We find that radiation induces a phonon bottleneck in the system with a time scale of ~5 $μ$s. The phonon bottleneck, in turn, drives the spin dynamics, allowing observation of thermally assisted resonant tunneling between spin states at the 100-ns time scale. Detailed numerical simulations quantitatively reproduce the data and yield a spin-phonon relaxation time of T1 ~ 40 ns.6 RevTeX pages, including 4 EPS figures, version accepted for publicationMesoscale and Nanoscale PhysicsMaterials Sciencetext