15min:

SERGIY KRASNOKUTSKI, JUNG SUP LEE AND DONG-SHENG YANG, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055.

Li-naphthalene (C₁₀H₈) and anthracene (C₁₄H₁₀) were produced by reactions of laser-vaporized Li atoms and ligand vapor. Although naphthalene has a sufficient vapor pressure at the room temperature, the vapor pressure of anthracene is rather low. Therefore, anthracene was co-vaporized by laser ablation of a target made of Li and organic powders. The pulsed-field ionization electron spectrum of Li-naphthalene shows a band origin at 35489 (5)~cm^-1 and extensive vibrational structures with intervals in the 140-1400~cm^-1 range. These vibrational structures were assigned to excitations of Li-naphthalene stretches and bends as well as in-plane and out-of-plane ring deformations. This complex has a Cs structure with Li located above one of the rings, and the naphthalene plane is significantly distorted in the neutral state. Unlike naphthalene where two six-membered rings are the same, the side and central rings are different in anthracene. Although vibrationally resolved electron spectrum has not been obtained, the photoionization efficiency spectrum of Li-anthracene exhibits two thresholds at 33800 (300)~and 37200 (200)~cm^-1, which correspond to ionization of two structural isomers with Li binding to the side and central rings, respectively.