  The recoil of atoms in arrays due to the emission or absorption of photons is
studied for sub-wavelength interatomic spacing. The atoms in the array interact
with each other through collective dipole-dipole interactions and with the
incident laser field in the low intensity limit. Shining uniform light on the
array gives rise to patterns of excitation and recoil in the array. These arise
due to the interference of different eigenmodes of excitation. The relation
between the recoil and the decay dynamics is studied when the array is in its
excitation eigenstates. The recoil experienced by a subradiant collective decay
is substantially larger than from independent atom decay. A method to calculate
the rate of recoil when steady state has been achieved with a constant influx
of photons is also described.
