  A simple method to control molecular translation with a chemical reaction is
demonstrated. Slow NO molecules have been produced by partially canceling the
molecular beam velocity of NO$_2$ with the recoil velocity of the NO
photofragment. The NO$_2$ molecules were photodissociated using a UV laser
pulse polarized parallel to the molecular beam. The spatial profiles of NO
molecules showed two peaks corresponding to decelerated and accelerated
molecules, in agreement with theoretical prediction. A significant portion of
the decelerated NO molecules stayed around the initial dissociation positions
even several hundred nanoseconds after their production.
