  We report measurements of spin transitions for GaAs quantum dots in the
Coulomb blockade regime, and compare ground and excited state transport
spectroscopy to direct measurements of the spin polarization of emitted
current. Transport spectroscopy reveals both spin-increasing and
spin-decreasing transitions as well as higher-spin ground states, and allows
g-factors to be measured down to a single electron. The spin of emitted current
in the Coulomb blockade regime, measured using spin-sensitive electron
focusing, is found to be polarized along the direction of the applied magnetic
field regardless of the ground state spin transition.
