Knowledge Bank

Gas-phase complexes of scandium with pyrene $(C16H20)$ and naphthalene $(C10H8)$ are produced by using laser ablation and a polycyclic aromatic hydrocarbon (PAH) oven in a pulsed molecular beam source. The resulting Sc-PAH complexes are characterized with pulsed field ionization-zero electron kinetic energy (PFI-ZEKE) photoelectron spectroscopy. The PFI-ZEKE spectrum of Sc-Pyrene exhibits vibrational progressions of 361 and $154cm-1$ and a vibrational spacing of $144cm-1$, with the band origin at $40937cm-1$. Through comparison with ab initio and Franck-Condon factor calculations, it is determined that this spectral profile arises from a Sc-pyrene complex in which the scandium atom is bound to the outer'' ring in an $\eta^{4}$ configuration. The $361 cm^{-1}$ progression is assigned to the $Sc^{+}$ -ring stretch and 154 and $144 cm^{-1}$ features are assigned to pyrene flying'' modes in the cation and neutral, respectively. For Sc-naphthalene, the spectrum shows four vibrational intervals of 389, 347, 298 and $112cm-1$, with the adiabatic ionization energy of $41192cm-1$. A preliminary analysis indicated the Sc atom is in an $\eta 2$ bonding mode in this complex. However, a detailed analysis is still in progress.