  We propose a promising scheme to decelerate a cw filtering out molecular beam
using a red-detuned quasi-cw semi-Gaussian laser beam. By using Monte-Carlo
simulation method, we demonstrate this optical Stark deceleration scheme, and
study its decelerated dynamic process for a cw ND3 molecular beam as well as
the dependence of the deceleration effect on the border width of the
semi-Gaussian beam. Our study shows that the proposed scheme can be used to
efficiently slow a cw ND3 molecular beam, and obtain a relative average
kinetic-energy loss of 9.33% by using a single semi-Gaussian beam with a well
depth of 7.3 mK.
