OFF-NORMAL EMISSION OF N-2 AND NORMAL EMISSION OF N2O PRODUCED BY THEDESORPTION 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 maxi mum emission of N-2 took place about 37 degrees off-normal to the surf ace in the [001] direction, however, the desorption of NO and the emis sion of N2O obeyed cos theta and cos(2) theta, respectively. On the ot her 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 a ppear during TPR. A sharp N-2 peak at 490 K corresponds to the desorpt ion mediated reaction of NO and a broad N-2 peak around 600 K is cause d 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 co s theta.