  The recombination dynamics of $^3$P oxygen atoms on cold amorphous solid
water to form triplet and singlet molecular oxygen (O$_2$) is followed under
conditions representative for cold clouds. It is found that both, formation of
ground state ($X ^3 \Sigma_{g}^{-}$) O$_2$ and molecular oxygen in the two
lowest singlet states ($a ^1\Delta_g$ and $b ^1\Sigma_g^+$) is possible and
that the species can stabilize. The relative proportions of the species is
approximately 1:1:1. These results also agree qualitatively with a kinetic
model based on simplified wavepacket simulations. As the chemical reactivity of
triplet and singlet O$_2$ is different it is likely that substantial amounts of
$a ^1\Delta_g$ and $b ^1\Sigma_g^+$ oxygen influences the chemical evolution of
cold clouds.
