LUMINESCENCE SPECTRA OF MASS-SELECTED PT-2 IN ARGON

We report on an observation of the luminescence and luminescence excit ation spectra of platinum dimers in an argon matrix. Samples were prod uced by sputtering from a metal target, followed by mass selection of dimer ions and codeposition with electrons and argon on a cold substra te. Emission is induced by Dumping into the 800-815 nm region with a t itanium-sapphire laser. Five sharp, intense spectral lines are observe d, with an average spacing of 197.4 +/- 3.3 cm(-1) and origin at 10 73 0.5 +/- 0.6 cm(-1). A much weaker vibrational progression in the emitt ing state gives omega(e)' = 179.2 +/- 0.6 cm(-1). Fluorescence excitat ion profiles were also obtained and are well simulated using data from previous gas-phase measurements. A rather wide separation of the orig ins of excitation and emission indicates rapid intersystem crossing in the excited state, with the possibility that our emission is not to t he dimer ground state.