Sisyphus polarization gradient laser cooling of Cr atoms on the J=3, J'=2, 3 and 4 transitions

Sisyphus polarization gradient laser cooling has been performed in a one-dimensional lin perpendicular to lin laser beam configuration on each of the three fine structure transitions 3d(5)4s(7)S(3)-3d(5)4p(7)P(2,3,4) of Cr-52. Hence for the first time Sisyphus polarization gradient cooling on a J(e) = J(g) transition with J(g) > 1 has been demonstrated. We have investigated the qualitative and quantitative differences between the cooling process for three transitions with J(e) = J(g) - 1, J(g), J(g) + 1 (J(g) > 1). A major qualitative difference of the laser cooling on the J(g) = 3 --> J(e) = 4 and J(g) = 3 --> J(e) = 2, 3 transitions has been observed as expected from simple theoretical arguments. In the case of J(e) less than or equal to J(g) sub-Doppler cooling is achieved when the laser detuning is blue. Even though the situation for the J(e) = 2 and J(e) = 3 case is qualitatively similar, we find quantitative differences which are in good agreement with Monte Carlo wavefunction simulations. For experiments where narrow velocity distributions are essential, such as atom lithography, these results can be applied.