  We investigate the zero-temperature coarsening dynamics of a chain of Ising
spins with a nearest-neighbor ferromagnetic and an nth-neighbor
antiferromagnetic interactions. For sufficiently large antiferromagnetic
interaction, the ground state consists of $n$ consecutive up spins followed by
n down spins, etc. We show that the asymptotic coarsening into this ground
state is governed by a multispecies reactive gas of elementary excitations. The
basic elementary excitations are identified and each decays at a different
power-law rate in time. The dominant excitations are domains of n+1 spins which
diffuse freely and disappear through processes which are effectively governed
by (n+1)-particle annihilation. This implies that the ground state is
approached slowly with time, as t^{-1/n}.
