Fourier Transform Spectra of the E(2)Pi(u)-X(2)Pi(g)((3/2)) System of CuCl(2)

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)Pi(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., omega(2) = 95.195(36) cm(-1), B(e) = 0.055106(3) cm(-1), epsilon = -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). Copyright 2000 Academic Press.