Spin noise spectroscopy and selection rules in highly purified 28silicon

We present our most recent experimental setup and results in qualifying the spin-lifetime and spin-selection rules of donor-bound and free electrons in highly purified 28silicon and natural silicon. Isotopically pure 28silicon is promising very long spin-coherence times due the missing inhomogeneous spin decoherence via nuclear hyperfine-interaction. The fragile measurements on localized spins in 28silicon will be realized by spin-noise spectroscopy based upon weakly interaction off-resonant Faraday-rotation while spin selective pump-probe measurements yield the spin selection rules at the Δ-band minimum in natural, slightly n-doped silicon.