Untersuchung der laserinduzierten Desorption mit zweidimensionalen-ortsaufloesenden und integralen Messmethoden: Anwendung auf des System NO/NiO(111)

The laserinduced desorption (Excimerlaser: #lambda#=193, 248 and 351 nm) of NO from epitaxially grown NiO(111)-surface at 90 K has been studied by fully state-selective and time-resolved determination of the energy distribution of desorbing molecules by (1+1)-REMPI detection (Resonance Enhanced Multiphoton Ionisation). A two dimensional imaging method has been developed and testet in order to simultaneous determine the energy and the angular distributions of selected quantum states. The experimental results provide evidence for the resonant nature of the nonthermal desorption-process for NO on a NiO(111) surface. For all rovibronic quantum states of the desorbed molecules, we found biomodal velocity flux distributions, independent of the desorption laser energy. We observed a laser induced photochemical reaction of NO on NiO(111) that changes the course of the velocity distribution and the desorption cross sections with NO_2 as a reaction product. The angular distribution of desorbed molecules shows a dependency between its width and the velocity of the molecules, i.e. increasing velocity the angular distribution becomes smaller along the surface normal. (orig.)SIGLEAvailable from TIB Hannover: RA 1396(1994,7) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman