Laser spectroscopy of the 3Σ+u(4 3P, 4 3P) state of Zn2

The doubly-excited 3Σ+u (4 3P, 4 3P) state of Zn2 was populated using pump and probe methods with time resolution. Structured excitation and fluorescence spectra were observed in the 300–330 nm region and are ascribed to 3Σ+u (4 3P, 4 3P)↔3Πg(4 3P) vibronic transitions, with partial resolution of the fine structure. An analysis of the spectra yielded the vibrational frequencies, relative energy, and relative equilibrium internuclear separations for the 3Σ+u and 3Πg states. The Zn2 excitation and fluorescence spectra contained a number of atomic lines whose origin was probed in a subsidiary experiment.