CAVITY RINGDOWN LASER-ABSORPTION SPECTROSCOPY AND TIME-OF-FLIGHT MASS-SPECTROSCOPY OF JET-COOLED GOLD SILICIDES

The cavity ringdown technique has been employed for the spectroscopic characterization of the AuSi molecule, which is generated in a pulsed supersonic laser vaporization plasma reactor. Fifteen rovibronic bands have been measured between 340 nm-390 nm, 8 of which have been analyz ed to yield molecular properties for the X and D (2) Sigma states of A uSi. This assignment is in disagreement with previous emission studies of AuSi, which had assigned the ground electronic state as a (2) Pi s tate. A time-of-flight mass spectrometer simultaneously monitors speci es produced in the molecular beam and has provided evidence for facile formation of polyatomic gold silicides. Comparison of AuSi with our r ecent results for CuSi and AgSi indicates regular bonding trends for t he three coinage metal silicide diatoms. (C) 1995 American Institute o f Physics.