  We show that the decay Bs -> J/psi f0(980), f0(980)->pi+ pi- can be used to
measure the CP violating phase in Bs mixing, -2\beta_s, and estimate the
sensitivity as +/- 0.050 rad, for 2/fb of LHCb data. After adding in the
related Bs -> J/psi eta', \eta' -> rho gamma mode, the sensitivity improves to
+/- 0.044 rad. Use of these CP eigenstates obviates the need for a transversity
analysis that must be used in the case of Bs -> J/psi phi decays.
