Dispersed fluorescence spectroscopy of jet-cooled AgAu and Pt-2

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 sta te vibrational levels were fit to provide ground state vibrational constant s of omega (")(e)=198.22+/-0.11 cm(-1) and omega (")(e)x(e)(")=0.512+/-0.00 2 cm(-1). A Franck-Condon calculation was performed using the experimental values of the ground and excited state vibrational frequencies and anharmon icities, 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 re sulting from four different excitations of Pt-2 was dispersed, providing vi brational 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 groun d state. A comparison to theoretical calculations suggests that both states have 0(g)(+) symmetry. Finally, a metastable state of Pt-2 lying at an unk nown energy was determined to have omega (e)=211 cm(-1), omega (e)x(e)=0.4 cm(-1). (C) 2001 American Institute of Physics.