  When liquid 3He is impregnated into silica aerogel a solid-like layer of 3He
atoms coats the silica structure. The surface 3He is in fast exchange with the
liquid on NMR timescales. The exchange coupling of liquid 3He quasiparticles
with the localized 3He spins modifies the scattering of 3He quasiparticles by
the aerogel structure. In a magnetic field the polarization of the solid spins
gives rise to a splitting of the scattering cross-section of for `up' vs.
`down' spin quasiparticles, relative to the polarization of the solid 3He. We
discuss this effect, as well as the effects of non-magnetic scattering, in the
context of a possible splitting of the superfluid transition for
$\uparrow\uparrow$ vs. $\downarrow\downarrow$ Cooper pairs for superfluid 3He
in aerogel, analogous to the A_1-A_2 splitting in bulk 3He. Comparison with the
existing measurements of T_c for B< 5 kG, which show no evidence of an A_1-A_2
splitting, suggests a liquid-solid exchange coupling of order J = 0.1 mK.
Measurements at higher fields, B > 20 kG, should saturate the polarization of
the solid 3He and reveal the A_1-A_2 splitting.
