Cryo Kinetics and Spectroscopy of Cationic Nickel Clusters: Rough and Smooth Surfaces

Abstract

The stepwise N 2 adsorption on size selected Ni 9 + and Ni 13 + clusters at 26 K is studied in a hybrid tandem ion trap instrument. Adsorption kinetics of these clusters in conjunction with infrared photon dissociation (IR-PD) spectroscopy of their cluster adsorbate complexes allows for the elucidation of various N 2 coverage and cluster size dependent effects, which are related to the rough Ni 9 + and smooth Ni 13 + cluster surface morphologies. Pseudo-first-order kinetic fits confirm consecutive adsorption steps by single exponential decays exclusively. The recorded IR-PD spectra of all observed cluster adsorbate complexes reveal IR active vibrational bands at frequencies of 2170–2260 cm –1, which coincides with the range of metal head-on coordinated N–N stretching modes. Density functional theory (DFT) calculations confirm the experiments and reinforce a possible isomerization with low N 2 coverage in the case of Ni 9 + .