Laser-induced fluorescence and Optical/Stark spectroscopy of PtC

Optical/Stark measurements have been performed on the (0,0) bands of both the A″ ¹Σ⁺ -X ¹Σ⁺ system (v₀ ≈ 12643 cm^-1) and the A′ ¹ Π- XΣ⁺ system (v₀ ≈ 13 196 cm^-1) of platinum monocarbide. The PtC molecules were produced in a pulsed supersonic molecular beam source following the reaction of laser ablated platinum vapor with a mixture of a few percent of methane in argon. The newly determined permanent electric dipole moments obtained are 1.94(2)D (A″ ¹Σ⁺) and 1.919(9)D (A′ ¹Π). These results are discussed in terms of a proposed molecular orbital correlation diagram for platinum containing diatomics. The laser-induced fluorescence spectrum of the (0,0)A″ ¹Σ⁺ - X ¹Σ⁺ transition of PtC has been re-recorded at high resolution (full width of half-maximum ∼40 MHz) and analyzed to yield rotational constants for the four most abundant isotopomers of PtC, extending the previous analysis [Appelblad, Nilsson, and Scullman, Phys. Scr. 7, 65 (1973)]. The anomalously large value (∼15 MHz) for the newly derived nuclear-spin rotation parameter, C₁(¹⁹⁵Pt), for the A″ ¹Σ⁺ state is discussed.