  We propose a laser cooling concept for the translational motion of molecules
which does not require repeated spontaneous emission by each molecule. The
cooling works by repetition of three main steps: velocity selection of a narrow
momentum width, deceleration of velocity selected molecules and accumulation of
the decelerated molecules by an irreversible process, namely by single
spontaneous emission. We develop a cooling model which enables analytical
description of the transient populations and entropies for the total molecular
system, the center of mass degree of freedom and the internal degrees of
freedom. Simulation shows that the cooling process can reduce a large momentum
width to a final width which in principle can be arbitrarily small. Center of
mass entropy is reduced while the internal entropy is increased after cooling.
We show that translational cooling can occur during coherent laser
interactions. The entropies change in consistency with the Araki-Lieb
inequality.
