Electronic spectroscopy of transition metal dimer

Abstract

This thesis reports laser spectroscopic studies of gas-phase transition metal dimers using laser ablation/reaction with free jet expansion and laser-induced fluorescence (LIF) spectroscopy technique. Themolecules studied in this work are palladium dimer (Pd2) and vanadium dimer (V2). Many compounds formed from these transition metals are important and functional catalysts in chemical reactions. Therefore, it is of great significance to start from the fundamental level to understand the properties and characteristics of the metal bonding and also the behavior of these metals when reacting with other chemicals.

The electronic transitions of Pd2and V2in the visible region were studied. Gas-phase Pd2and V2moleculeswereproduced by laser ablation of palladium and vanadium metal rod, respectively. For the Pd2molecule, eleven vibrational bands were recorded and analyzed, and have been assigned to the 〖[17.1]〗^3 □_g□ X^3 □_u^+ transition system. The bond length and vibrational frequency of the ground X^3 □_u^+ state were determined to be 2.47 Å and 211.38 cm-1, respectively. This is the first experimental investigation of the electronic transitions of Pd2.For the V2molecule,six vibrational bands were observed and assigned to a new 〖[19.6] 〗^3 □_u^□□ X^3 □_g^□ transition system. Molecular constants for the 〖[19.6] 〗^3 □_u^□ excited state were obtained from high-resolution LIF spectra. The electronic structure of the Pd2andV2molecules was discussed in detail using molecular orbital energy level diagrams, which is important for understanding the nature of chemical bonding in these dimers. Comparison of the transition metal dimers studied in this work with other dimers is also presented.