15min:

S. KRASNOKUTSKI AND D. S. YANG, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055.

Aluminum uracil (Al-C₄H₄N₂O₂) was formed by the interaction of the laser-vaporized metal and nucleobase in a pulsed nozzle cluster source. Electronic spectra of the complex were measured by using pulsed field ionization zero electron kinetic energy spectroscopy. The spectroscopic measurements determine the ionization energy of 43064(7)~cm^-1, two Al⁺-uracil stretches of 303 and 614 cm^-1, and Al⁺/Al-uracil out-of-plane/in-plane bends of the same frequency of 51~cm^-1. The 303~cm^-1 stretch is characterized largely by the Al⁺ displacement, where the 614~cm^-1 stretch is described by the ligand dislocation. The complex has a number of the low-energy conformers due to multiple binding sites of uracil. The comparison of the ZEKE spectrum and theoretical calculations establishes that the complex favors Al binding with the O4 atom under C_s symmetry.