Resonant two-photon ionization spectroscopy of jet-cooled PtSi

Jet-cooled diatomic PtSi, produced in a laser ablation supersonic expansion source, has been spectroscopically investigated between 17 400 and 24 000 cm(-1) by resonant two-photon ionization spectroscopy. Two vibrational prog ressions are observed and identified as the [15.7]Omega'=1 <-- X (1)Sigma() and [18.5]Omega'=1 <-- X (1)Sigma(+) band systems. Three bands in the for mer system and six bands in the latter system were rotationally resolved an d analyzed, leading to bond lengths of r(e)'=2.1905(13) Angstrom and r(e)'= 2.2354(3) Angstrom for the [15.7]Omega'=1 and [18.5]Omega'=1 states, respec tively. The Omega"=0 ground state of PtSi is assigned as a (1)Sigma(+) stat e, in agreement with previous work and with the assigned ground states of t he isovalent NiC, PdC, PtC, and NiSi molecules. The ground state bond lengt h of PtSi is given by r(0)"=2.0629(2) Angstrom. A Rydberg-Klein-Rees analys is of the ground and excited state potential energy curves is presented, al ong with a discussion of the chemical bonding and a comparison to the isoel ectronic molecule, AlAu. Evidence is presented for a double bond in PtSi, a s opposed to a single bond in AlAu. (C) 2000 American Institute of Physics. [S0021-9606(00)00707-8].