R.E. Drullinger and R. N. Zare, “Optical Pumping of Molecules,”J. Chem. Phys. 51, 5532-5542 (1969). R.E. Drullinger and R. N. Zare, “Optical Pumping of Molecules,”J. Chem. Phys. 51, 5532-5542 (1969).