Theoretical study of spectroscopic parameters of alkali -Al and alkaline earth-Al dimers

Abstract

The ground states of alkali-Al dimers (AlLi, AlNa, AlK, AlRb and AlCs) and alkaline earth-Al dimers (AlBe, AlMg, AlCa, AlSr and AlBa) along with their monovalent anions and cations were assigned based on the results of calculations. Bond lengths re, harmonic vibrational frequencies ωe and dissociation energies D0 of these species were obtained. For neutral dimers, we also calculated adiabatic electron affinities (EA) and adiabatic ionization energies (IE). The present results are in agreement with the available experimental and other theoretical data. The ground state symmetry of AlLi, AlNa, AlK, AlRb and AlCs is 1 ∑+. The ground state symmetry of AlBe+, AlMg +, AlCa+, AlSr+ and AlBa+ is also 1 ∑+. The ground state of AlLi-, AlNa -, AlK-, AlRb- and AlCs- is 2 Π, and is the same as in the isoelectronic neutral Al-alkaline-earth dimers. For both the alkali-Al and alkaline earth-Al neutral AlX species, the bond length increases monotonously with increasing atomic number of X. For the alkali-Al ions, energies of dissociation via the channels AlX- → Al + X- and AlX+ → Al + X + are smaller than the energies of dissociation via the channel AlX- → X + Al- andAlX+ → X + Al +, respectively. While the opposite dissociation manner is found for alkaline earth-Al anions. © 2008 Springer-Verlag.