Resonant two-photon ionization spectroscopy of jet-cooled PtSi

Abstract

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 progressions are observed and identified as the [15.7]Ω′=1←X 1Σ+ and [18.5]Ω′=1←X 1Σ+ band systems. Three bands in the former system and six bands in the latter system were rotationally resolved and analyzed, leading to bond lengths of re′=2.1905(13) Å and re′=2.2354(3) Å for the [15.7]Ω′=1 and [18.5]Ω′=1 states, respectively. The Ω″=0 ground state of PtSi is assigned as a 1Σ+ state, in agreement with previous work and with the assigned ground states of the isovalent NiC, PdC, PtC, and NiSi molecules. The ground state bond length of PtSi is given by r0″=2.0629(2) Å. A Rydberg–Klein–Rees analysis of the ground and excited state potential energy curves is presented, along with a discussion of the chemical bonding and a comparison to the isoelectronic molecule, AlAu. Evidence is presented for a double bond in PtSi, as opposed to a single bond in AlAu.