Datensatz

Zusammenfassung

The interaction of hydrogen with singly rhodium doped aluminum clusters Al_nRh⁺ (n = 1–12) is investigated experimentally by a combination of time-of-flight mass spectrometry and infrared multiple photon dissociation (IRMPD) spectroscopy. Density functional theory (DFT) is employed to optimize the geometric and electronic structures of bare and hydrogenated Al_nRh⁺ clusters and the obtained infrared spectra of hydrogenated clusters are compared with the corresponding IRMPD spectra. The reactivity of the Al_nRh⁺ clusters toward H₂ is found to be strongly size-dependent, with n = 1–3, and 7 being the most reactive. Furthermore, it is favorable for H₂ to adsorb molecularly on Al₂Rh⁺ and Al₃Rh⁺, while it prefers dissociative adsorption on other sizes. The initial molecular adsorption of H₂ is identified as the determining step for hydrogen interaction with the Al_nRh⁺ clusters, because the calculated molecular adsorption energies of H₂ correlate well with the experimental abundances of the hydrogenated clusters. Natural charge populations and properties of the Al_nRh⁺ clusters are analyzed to interpret the observed size-dependent reactivity.