Off-normal emission of N-2 and normal emission of N2O produced by the desorption mediated reaction of NO on Pd(110)

8The spatial distribution of both N-2 and N2O produced at 490 K by the desorption mediated reaction of NO from Pd(110) was studied. The maximum emission of N-2 took place about 37 degrees off-normal to the surface in the [001] direction, however, the desorption of NO and the emission of N2O obeyed cos theta and cos(2) theta, respectively. On the other hand, the spatial distribution of NO and N-2 toward the [1(1) over bar0$] direction obeyed cos(1.6)theta and Cos(4.2)theta, respectively. In a flow of a mixture of 1 x 10(-8) Torr NO and 1 x 10(-6) Torr H-2, a sharp N-2 peak at 490 K and a broad peak with a maximum at 600 K appear during TPR. A sharp N-2 peak at 490 K corresponds to the desorption mediated reaction of NO and a broad N-2 peak around 600 K is caused by the catalytic reaction of NO and H-2. In the [001] direction, the former N-2 peak had a maximum at 37 degrees off-normal to the surface, but the latter N-2 peak produced by the catalytic reaction obeyed cos theta.