15min:

JAMIE GENGLER, TIMOTHY STEIMLE AND JINHAI CHEN, Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287.

The reaction products of laser ablated platinum with an ammonia/argon supersonic gas expansion mixture have been monitored in the 13500 cm^-1 to 12400 cm^-1 spectral region using laser induced fluorescence (LIF) spectroscopy. Four band features with heads near 13440 cm^-1, 13250 cm^-1, 13120 cm^-1, and 12435 cm^-1 were detected. Analysis of the dispersed fluorescence suggests that the carriers of the latter three bands are Pt₂, PtN, and PtN. Possible electronic transition assignments for these systems based upon existing electronic structure predictions for Pt₂ and PtN will be given. The dispersed fluorescence spectrum for the 13440 cm^-1 band, which exhibits two progressions having G_v of 450 cm^-1 and 650 cm^-1, suggests that the carrier of this band is polyatomic. The excitation LIF and dispersed LIF spectra are not altered upon substitution of NH₃ with ND₃ suggesting that the carrier is PtN₂ with linear asymmetric geometry'. The high resolution LIF spectrum (FWHM = 35 MHz) of the 13440 cm^-1 band of a molecular beam sample reveals rotational structure which can be assigned to the major ¹⁹⁴Pt, ¹⁹⁵Pt, ¹⁹⁶Pt, and ¹⁹⁸Pt isotopomers. Progress on the analysis of the high resolution LIF and optical Stark measurements for the 13440 cm^-1 band will be presented.