title: Experimental and theoretical study of the electronic spectrum of BeAl.
abstract: The electronic structure of BeAl was investigated by laser induced fluorescence and resonance enhanced multiphoton ionization spectroscopy. BeAl was formed by pulsed laser ablation of a Be/Al alloy in the presence of helium carrier gas, followed by a free jet expansion into vacuum. In agreement with recent ab initio studies, the molecule was found to have a (2)Pi(1/2) ground state. Transitions to two low lying electronic states, (2)2Pi1/2(v') <-- X 2Pi1/2 (v'' = 0) and (1)2Delta(v') <-- X 2Pi1/2 (v'' = 0,1), were observed and rotationally analyzed. An additional band system, identified as (4)2Sigma+(v') <-- X 2Pi1/2, was found in the 28 000-30 100 cm(-1) energy range. This transition exhibited an unusual pattern of vibrational levels resulting from an avoided crossing with the (5)2Sigma+ electronic state. New multi-reference configuration interaction calculations were carried out to facilitate the interpretation of the UV bands. An ionization energy of 48 124(80) cm(-1) was determined for BeAl from photoionization efficiency (PIE) measurements. Fine structure in the PIE curve was attributed to resonances with Rydberg series correlating with vibrationally excited states of the BeAl+ ion. Analysis of this structure yielded a vibrational frequency of 240(20) cm(-1) for the cation.
authors.affiliation: Department of Chemistry, Emory University, Atlanta, GA 30322, USA.
authors.forename: Jeremy M
authors.initials: JM
authors.lastname: Merritt
authors.forename: Vladimir E
authors.initials: VE
authors.lastname: Bondybey
authors.forename: Michael C
authors.initials: MC
authors.lastname: Heaven