Fourier Transform Spectra of the E2Πu–X2Πg(3/2) System of CuCl2: 2. Rovibronic Levels of the Ground State up to 4000 cm−1

Abstract High-resolution Fourier transform spectra of the laser-induced fluorescence of 63 Cu 37 Cl 2 produced in a cell have been recorded following excitation of a single vibronic level of the E 2 Π u electronic state. Fluorescence occurs in combination bands to a broad spread of levels in the ground electronic state. A global vibronic model is proposed for the ground state based on an effective Hamiltonian, which fits the experimental data (2782 fluorescence lines, lower state quantum numbers: v 1 = 0–6, v 2 = 0–2, v 3 = 0–6, and J = 4 1 2 –80 1 2 ) to 0.019 cm −1 rms error. Vibrational, rotational and Renner–Teller parameters are obtained (e.g., ω 2 = 95.195(36) cm −1 , B e = 0.055106(3) cm −1 , ϵ = −0.1893(28)). A revised value for the equilibrium internuclear distance Cu–Cl is deduced: r e (Cu–Cl) = 0.20341(3) nm. The energy diagram of vibronic levels in the ground state is plotted up to 4000 cm −1 .