Soft-landing Experiments of Size-selected Functional Nanoclusters

Abstract

Organometallic sandwich clusters of M (benzene)₂ (M = V and Cr) synthesized in gas phase reaction are soft-landed onto a self-assembled monolayer of n-alkanethiol (C4-C22 SAM) at a collision energy of 10-20eV. The resulting adsorption states and thermal desorption kinetics of the soft-landed clusters are studied with infrared reflection absorption spectroscopy and temperature-programmed desorption. The clusters keep their native sandwich structure intact on the SAM substrate. The soft-landed cluster are oriented with their molecular axes largely tilted off the surface normal of the SAM substrate, and exhibit unusually large desorption activation energies (E_d = ∼130 kJ/mol). The desorption of the embedded clusters in the SAM is suppressed to around room temperature, and may be associated with the crystal-rotator phase transitions of the SAM matrix.