Reactions of iron clusters with hydrogen. III. Laser-induced desorption of H2 by multiphoton absorption

Abstract

Multiphoton absorption and ionization of hydrogenated (or deuterated) iron clusters generally leads to desorption of a specific number of H2 (or D2) molecules for a given cluster size and a given number of photons absorbed. Ionization via single photon absorption occurs without desorption. Experimental results demonstrate that the fragmentation pattern resulting from multiphoton absorption is independent of whether desorption precedes or follows ionization. From the number of desorbed molecules and the number and energy of absorbed photons an estimate of 1.3 eV for the desorption energy can be made without the necessity of modeling the desorption process. A simple statistical model of the process provides similar estimates of the desorption energies, and indicates that the energy has some dependence on cluster coverage.