COHERENCE EFFECTS IN THE POLARIZATION OF LYMAN-ALPHA FLUORESCENCE FOLLOWING PHOTODISSOCIATION OF H-2 AND D-2

The polarization of the Lyman-alpha fluorescence following photodissociation of H-2 and D-2 into fragments in the 1s and 2l states has been determined as a function of the excess energy of the fragments. The predicted oscillations of the polarization as a function of excess energy were clearly observed. In addition, the theoretical polarization was recalculated including the stronger B-B' coupling scheme as well as collisional effects on the polarization. The collisional effects include the quenching processes for H(2s) and H(2p) and disaligning collisions. The calculations reproduced the experimental data quite well giving a cross section for the disaligning collisions of (1.0+/-0.2). 10(-14) cm(2) for H-2 and D-2 at a gas temperature of 137 K in the relative velocity range of 2 to 7 km s(-1). This can be considered as a proof of the theoretical predictions on the interference effects between the continua excited coherently. (C) 1995 American Institute of Physics.