Dispersed fluorescence spectroscopy of jet-cooled AgAu and Pt2

Dispersed fluorescence spectroscopy has been used to study jet-cooled AgAu and Pt-2. Fluorescence resulting from the excitation of five bands of the A<--X (1)<Sigma>(+) system of AgAu was dispersed, and 51 measured ground state vibrational levels were fit to provide ground state vibrational constants of omega (")(e)=198.22+/-0.11 cm(-1) and omega (")(e)x(e)(")=0.512+/-0.002 cm(-1). A Franck-Condon calculation was performed using the experimental values of the ground and excited state vibrational frequencies and anharmonicities, providing an estimate of the change in bond length upon excitation of the A<--X system of <Delta>r(e)=0.214+/-0.005 Angstrom. Fluorescence resulting from four different excitations of Pt-2 was dispersed, providing vibrational constants for the ground and two low-lying excited states. Ground state vibrational constants of omega (e)=222.3 cm(-1) and omega (e)x(e)=0.62 cm(-1) were obtained, based on the analysis of 16 measured ground state vibrational levels. In addition, a low-lying excited state was located at T-0=2877 cm(-1), with omega (e)=197 cm(-1). This state perturbed the ground state, from which it was deduced that it has the same symmetry as the ground state. A comparison to theoretical calculations suggests that both states have 0(g)(+) symmetry. Finally, a metastable state of Pt-2 lying at an unknown energy was determined to have omega (e)=211 cm(-1), omega (e)x(e)=0.4 cm(-1). (C) 2001 American Institute of Physics.